INSIVUMEH and CONRED reported that activity at Fuego increased on 18 November, heralding the fifth effusive phase of 2018. Incandescent material was ejected 200-300 m above the crater rim and a lava flow in the Ceniza (SSW) drainage reached 2.5 km in length. Avalanches of material from the lava flow reached vegetated areas. Explosions occurring at a rate of 8-17 per hour generated ash plumes that rose at least 1.2 km and drifted 20-25 km W and SW. Ashfall was reported in areas downwind including Morelia (9 km SW), Santa Sofia (12 km SW), Sangre de Cristo (8 km WSW), Panimaché I and II (8 km SW), and Finca Palo Verde. Volcanic material also accumulated in the Taniluyá (SW) and Seca (W) drainages causing increased risk of avalanches. Later that day explosions became stronger, and incandescent material was ejected 400 m high. Ashfall continued to be reported in local communities. CONRED reported that a portion of National Route 14 was closed, and evacuations began in some local areas.

Strombolian activity continued to intensify on 19 November with stronger explosions and increased seismicity. Incandescent material was ejected as high as 1 km above the crater. Ash plumes rose as high as 3.2 km and drifted 20-60 km W, SW, and NE. Pyroclastic flows descended the Seca drainage, and, along with ash emissions from the crater, caused ashfall in multiple areas including Santa Sofia, Sangre de Cristo, Panimaché I and II, and Finca Palo Verde. The lava flow in the Ceniza drainage advanced to 3 km long and produced avalanches from the flow front. Avalanches of tephra also descended the Seca, Ceniza, Taniluyá, Las Lajas, and Honda (E) drainages, reaching vegetated areas. CONRED noted that 3,925 people had been evacuated.

Guatemala's Volcán de Fuego was continuously active throughout 2017, and has been erupting vigorously since 2002; historical observations of eruptions date back to 1531. These eruptions have resulted in major ashfalls, pyroclastic flows, lava flows, and damaging lahars. Reports of activity are provided by the Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia (INSIVUMEH), and aviation alerts of ash plumes are issued by the Washington Volcanic Ash Advisory Center (VAAC). Satellite data from NASA, NOAA, and other sources provide valuable information about heat flow and gas emissions.

Activity remained high at Fuego throughout July-December 2017. Background levels of activity included frequent explosions (4-6 per hour) with incandescent material rising 150 m above the summit and sending blocks 200 m down the flanks. Block avalanches commonly traveled down the major ravines for hundreds of meters. Ash plumes regularly rose 500-1,000 m above the summit (4.3-4.8 km altitude); ashfall affected communities SW of the summit within 15 km every week. During the multiple short-lived (48-hour or less) eruptive episodes, the hourly explosion rates increased significantly (6-12 per hour), and incandescent material often rose 300 m above the summit; one or more lava flows would also travel more than a kilometer down major ravines. Higher ash plumes (often rising to 5-6 km altitude) during the eruptive episodes sent ash plumes drifting hundreds of kilometers in various directions causing ashfall in cities tens of kilometers away in various directions. Pyroclastic flows often accompanied the eruptive episodes. Seven episodes were reported by INSIVUMEH during July-December 2017 (table 17); they are clearly discernible as periods of higher heat flow in the MIROVA thermal anomaly data (figure 73) as well.

Table 17. Eruptive episodes at Fuego during July-December 2017. Information provided primarily by INSIVUMEH. Some ash plume information is from the Washington VAAC.

Figure 74. Incandescent material was ejected over a hundred meters above the summit of Fuego and blocks of material traveled hundreds of meters down the flank on 9 July 2017. Courtesy of INSIVUMEH and OVFGO (Reporte Semanal de Monitoreo: Volcán Fuego (1402-09), Semana del 08 al 14de julio 2017).

The Washington VAAC reported dense ash emissions seen in satellite data on 10 July extending WNW 60 km from the summit at 4.6 km altitude. They noted that ashfall was reported 10 km SW from the summit the following morning. The 6th eruptive episode of the year occurred on 11-12 July 2017. Explosions generated ash plumes that rose as high as 1.3 km above the crater and drifted 35 km W, and shock waves rattled nearby structures. Ash fell in areas to the SW. Two lava flows were fed by lava fountains 150-250 m high; one flow traveled 2.3 km down the Las Lajas drainage and another traveled 1.7 km down the Santa Teresa (SW) drainage. The increased activity levels lasted for about 31 hours, with tens of explosions. Weak-to-moderate explosions continued afterwards, generating ash plumes that rose 850 m and drifted 6 km W.

Multiple explosions continued generating ash plumes and block avalanches during 13-14 July. On 16 July, a 30-m-wide, 2-m-deep, hot lahar descended tributaries of the Pantaleón (W) drainage, carrying blocks more than 2 m in diameter, branches, and tree trunks. The lahars again overtook the road between communities on the SW flank, isolating the village of Sangre de Cristo (8 km WSW) and the Palo Verde estate. The Washington VAAC estimated that the ash plumes released early on 16 July rose to 5.2 km altitude, and drifted SE from the summit. By afternoon they had risen to 5.8 km and were drifting SW, extending about 75 km. Explosions during 17-18 July produced dense ash plumes that drifted 15 km W and NW causing ashfall in Panimache, Morelia, and Santa Sofía. Satellite imagery on 19 July showed an ash plume extending 65 km WNW of the summit in a narrow band at 4.3 km altitude. Similar plumes were reported daily between 19-23 July at 4.3-4.9 km altitude drifting generally W up to about 50 km before dissipating (figure 75).

Figure 75. Ash emissions were reported almost daily from Fuego during July 2017. A small pulse of ash on 20 July was captured on the Panimaché I webcam (10 km SW) in this view looking NE in the early morning. Courtesy of OVFGO-INSIVUMEH (Reporte Semanal de Monitoreo: Volcán Fuego (1402-09), Semana del 15 al 21 de julio 2017).

Activity during August 2017. MODVOLC thermal alerts that were issued on 28 and 30 July confirmed the continuing incandescent summit activity which produced block avalanches down the major drainages. Multiple daily alerts were also issued during 15 days of August. Coordinadora Nacional Para la Reduccion de Desastres (CONRED) reported increased activity on 4 August that included 300-m-high ejections of incandescent material and a lava flow that traveled 600 m down the Ceniza ravine. During 7-8 August two lava fountains rose 150 m high, prompting INSIVUMEH to announce the seventh effusive episode at Fuego in 2017. The fountains fed lava flows, 1.5 km and 700 m long, in the Ceniza and the Santa Teresa ravines (figure 76). Explosions (occurring at a rate of 6-8 per hour) produced ash plumes that drifted 20 km W, causing ashfall in Panimache, Morelia, Santa Sofía, El Porvenir, and Yepocapa. The Washington VAAC also noted increasing ash emissions on 7 August. Weather clouds prevented observations from satellite images on 7 and 8 August, but the VAAC reported a "" strong hotspot in infrared imagery on 8 August. Although the lava flow in the Ceniza drainage remained active, explosive activity decreased to an average of three explosions per hour the following week, with ash emissions rising to 4.4-4.6 km and drifting 10 or more km W and SW, bringing ashfall to communities on the W and SW flank.

Activity intensified again during 19-20 August, when constant explosions generated ash plumes that rose 2.3 km above the crater and drifted more than 50 km W and SW. INSIVUMEH reported that the eighth effusive episode at Fuego in 2017 began on 20 August and lasted for about 48 hours. Two lava fountains, each 300 m high, fed lava flows that traveled 1.4 km SSW down the Ceniza ravine and 1.2 km W down the Seca (Santa Teresa) ravine (figure 77). Incandescent block avalanches occurred throughout the crater. Pyroclastic flows (figure 78) were concentrated in the Santa Teresa ravine, possibly filling the drainage with deposits (similar to activity from 5 May) and increasing the chances for lahars. A bright hotspot was visible in satellite imagery from 19-21 August. Seismicity remained elevated through 21 August. During 21 August, the Washington VAAC reported the ash plume near 5.5 km altitude extending 75 km WNW. A remnant cloud of ash was detected in satellite imagery over 200 km WNW of the summit in extreme SE Mexico late on 21 August.

Figure 78. A pyroclastic flow descends the Santa Teresa ravine at Fuego during eruptive episode 8 on 21 August 2017 in this view from the Panimaché I webcam. Courtesy of OVGFO-INSIVUMEH (Reporte Semanal de Monitoreo: Volcán de Fuego (1402-09), Semana del 19 al 25 de agosto 2017).

INSIVUMEH reported that on 25 August multiple lahars descended the Pantaleón, Cenizas, El Jute, and Las Lajas drainages on Fuego's W, SSW, and SE flanks. The lahar in the Pantaleón river (fed by the Santa Teresa and El Mineral rivers) was 35 m wide, 2.5-3 m deep, and carried trees and blocks more than 2-3 m in diameter. The Cenizas lahar was about 25 m wide, 3 m deep, and carried blocks up to 2 m in diameter. The lahars in El Jute and Las Lajas drainages were 20 m wide, 1.5 m deep, and carried tree debris and blocks up to 2 m in diameter.

Explosions during 26-29 August generated ash plumes that rose as high as 950 m above the crater and drifted 7-12 km SW, W, and NW. The Washington VAAC reported near continuous emissions of ash on 28 August moving WSW and extending about 100 km at 4.6 km altitude, rising to 5.8 km altitude the following day. Incandescent material was ejected 100-200 m above the crater rim and caused avalanches of material around the crater area. Explosions were audible within a 20-km radius, and shock waves vibrated local structures. Ash fell in areas downwind including Panimache I and II, Morelia, Finca Palo verde, Sangre de Cristo, and El Porvenir. On 29 August, lahars 10 m wide and 1.5 m deep again descended the Santa Teresa and El Mineral drainages, carrying tree debris and blocks up to 2 m in diameter.

Activity during September 2017. Lahars were reported in the Santa Teresa and El Mineral drainages intermittently during September. Ash emissions continued to cause ashfall in communities within 10 km W and SW throughout the month. Continuous ejection of incandescent blocks rose 200-300 m above the crater and sent material 300 m down the flanks. The Washington VAAC reported a continuous plume of ash detected in satellite imagery and in the webcam extending about 95 km WSW on 8 September at 4.6 km altitude. INISVUMEH reported that the increase in activity during 8 September fed a lava flow that traveled 800 m down Barranca Seca.

The ninth eruptive episode of 2017 began late on 12 September and lasted about 35 hours (figure 79). Pyroclastic flows descended the Seca (Santa Teresa) ravine on the W flank, along with a lava flow that traveled 1.3 km during the episode. Ashfall was reported in Morelia, Palo Verde Estate, Sangre de Cristo, El Porvenir, Santa Sofía, and Panimaché I and II. The Washington VAAC reported that an ash plume extended about 65 km N from the summit on 13 September at 4.6 km altitude. After several days of weather clouds obscuring the satellite images, they reported a plume drifting W on 17 September extending 95 km from the summit. A hotspot intermittently appeared during 13-17 September.

Seven lahars were recorded during September in the main ravines of Fuego, on days 3, 4, 5, 6, 8, 27, and 29, as a result of the unusually large amount of rainfall during the month (1,059 mm) (figure 81). The larger ones at the beginning of the month contained blocks up to 3 m in diameter, and many were warm enough to generate steam with strong odors of SO2. Several roads were damaged.

Activity during October 2017. Overall activity was quieter during October 2017. Background levels of activity included incandescent material rising up to 250 m above the summit and falling a similar distance down the flanks, and ash plumes rising to 4.4-5.0 km altitude and drifting more than 25 km W, NW, and E. Eight to twelve explosions per hour were not uncommon, although 4-6 per hour were more typical. A few of the block avalanches traveled 2 km down the flanks. The communities that experienced persistent ashfall were all located 10-20 km SW, and included Morelia, Palo Verde Farm, Sangre de Cristo, El Porvenir, Santa Sofía, and Panimaché I and II. Due to the wind conditions and increased activity during the first week of October, ashfall was also reported farther away in Guatemala City (40 km NE), Antigua Guatemala, Villa Nueva (30 km ENE) and San Miguel Petapa (35 km ENE). INSIVUMEH reported three increases in explosive activity during the month on 2, 3, and 5 October, but they did not develop into eruptive episodes.

Four lahars were reported on 1, 2, and 4 October in the Seca and Mineral drainages. They carried blocks of volcanic rocks and debris as large as 3 m in diameter and were 6-12 m wide and 1-2 m deep. The Washington VAAC reported a series of explosions on 4 October, after which ash emissions were seen in multispectral imagery at 5.2 km altitude drifting SW that reached as far as 75 km. They reported occasional puffs of ash on 15 October extending up to 95 km W of the summit. By 17 October, imagery showed continuous emissions with an ash plume extending 95 km SSW from the summit before dissipating. A possible ash plume was reported by the Washington VAAC on 31 October extending 45 km W from the summit at 4.3 km altitude.

Activity during November 2017. There were numerous periods of intermittent ash emissions during November. Continuous emissions often drifted 65-100 km or more SW or W at altitudes around 4.6-5.2 km during periods of activity. INSIVUMEH reported that during 2-3 November tremor at Fuego increased. Explosions during the first week averaged 5-8 per hour and ash plumes rose as high as 1.3 km above the crater. Incandescent material was ejected 300 m above the crater, causing avalanches that were confined to the crater. The 11th eruptive episode in 2017 began on 5 November and lasted for two days. Lava flowed 1-1.2 km W down the Seca drainage and 800 m SSW down the Ceniza drainage. Avalanches of material from the ends of the lava flows descended the flanks and reached vegetated areas.

Ashfall was reported in areas downwind in the communities 8-12 km SW including Morelia, Santa Sofia, Palo Verde Farm, and Panimaché I and II throughout the month. Shockwaves from explosions often rattled windows and roofs around the volcano. Avalanche blocks were reported in the Cenizas, Trinidad, Taniluyá and Seca canyons. Multiple VAAC reports were issued on 25 days of November, and multiple daily MODVOLC thermal alerts were issued on 20 days of the month. On 10 November the emissions extended about 275 km WSW from the summit. A lahar during the third week descended the Seca and el Mineral drainages.

Activity during December 2017. Explosions averaged 4-8 per hour during most of December sending incandescent material 200-250 m above the crater. INSIVUMEH reported that the 12th eruptive episode at Fuego in 2017 began on 10 December and, based on seismicity, lasted for about 36 hours. Ash plumes from moderate-to-strong explosions rose as high as 1.2 km above the crater rim and drifted 20 km S and SW. Lava flowed as far as 1.5 km W down the Seca (Santa Teresa), SW down the Taniluyá, and SSW down the Ceniza ravines. Ash fell many times in the communities of La Rochela, San Andrés Osuna, Morelia, and Panimaché I and II. On 12 December there was an average of 10 explosions per hour, generating avalanches in the Ceniza and Taniluyá drainages and ashfall in nearby areas. Ashfall was also reported in San Miguel Dueñas, Alotenango, and Ciudad Vieja (13.5 km NE) on 14 December.

Multiple MODVOLC thermal alerts appeared on 20 days during December, and the Washington VAAC issued 91 reports of continuous or intermittent ash plume activity. During eruptive episode 12 on 11 December, they reported an intense hot spot seen at the crater in satellite imagery despite meteoric cloud cover. For most of the second half of December, either continuous or intermittent ash emissions drifted 100-150 km WNW from the summit before dissipating. The Washington VAAC reported an ash emission on 20 December drifting WNW at 5.8 km altitude that extended over 300 km from the summit. A remnant of the plume was observed almost 450 km away late on 20 December before dissipating. Plumes were repeatedly observed over 200 km from the summit during 20-25 December.

INSIVUMEH and CONRED reported that activity at Fuego increased on 18 November, heralding the fifth effusive phase of 2018. Incandescent material was ejected 200-300 m above the crater rim and a lava flow in the Ceniza (SSW) drainage reached 2.5 km in length. Avalanches of material from the lava flow reached vegetated areas. Explosions occurring at a rate of 8-17 per hour generated ash plumes that rose at least 1.2 km and drifted 20-25 km W and SW. Ashfall was reported in areas downwind including Morelia (9 km SW), Santa Sofia (12 km SW), Sangre de Cristo (8 km WSW), Panimaché I and II (8 km SW), and Finca Palo Verde. Volcanic material also accumulated in the Taniluyá (SW) and Seca (W) drainages causing increased risk of avalanches. Later that day explosions became stronger, and incandescent material was ejected 400 m high. Ashfall continued to be reported in local communities. CONRED reported that a portion of National Route 14 was closed, and evacuations began in some local areas.

Strombolian activity continued to intensify on 19 November with stronger explosions and increased seismicity. Incandescent material was ejected as high as 1 km above the crater. Ash plumes rose as high as 3.2 km and drifted 20-60 km W, SW, and NE. Pyroclastic flows descended the Seca drainage, and, along with ash emissions from the crater, caused ashfall in multiple areas including Santa Sofia, Sangre de Cristo, Panimaché I and II, and Finca Palo Verde. The lava flow in the Ceniza drainage advanced to 3 km long and produced avalanches from the flow front. Avalanches of tephra also descended the Seca, Ceniza, Taniluyá, Las Lajas, and Honda (E) drainages, reaching vegetated areas. CONRED noted that 3,925 people had been evacuated.

INSIVUMEH and CONRED reported an increase in seismicity and in the number of explosions at Fuego on 31 October. Ash plumes during 31 October-5 November rose 1 km above the summit and drifted 15 km W and SW. Ashfall was reported in areas downwind including Morelia (9 km SW), Santa Sofia (12 km SW), Sangre de Cristo (8 km WSW), Panimaché (8 km SW), and San Pedro Yepocapa (8 km NW). By 2 November a lava flow had traveled 300 m down the Ceniza (SSW) drainage, and by 4 November lava flows 600 m long descended the Ceniza and Taniluyá (SW) drainages. Explosions on 4 November produced shock waves that rattled nearby structures, and on 5 November ejected incandescent material 200 m high. INSIVUMEH reported another increase of activity on 6 November characterized by a period of constant explosions, and ash plumes rising over 1 km and drifting 20 km W and SW. Ashfall was reported in multiple areas including Panimaché, El Porvenir, Morelia, Santa Sofia, Sangre de Cristo, Finca Palo Verde, and San Pedro Yepocapa. Incandescent material was ejected 200-300 m high and caused avalanches that reached vegetated areas in the Seca and Taniluyá drainages. A 1-km-long lava flow was active in the Ceniza drainage. Shock waves from explosions vibrated local houses.

INSIVUMEH and CONRED reported that on 12 October a new phase of activity began at Fuego, characterized by lava fountains rising as high as 400 m above the crater rim, avalanches of incandescent material down the W and SSW flanks, increased rumbling, and a lava flow traveling 1 km down the Santa Teresa (W) drainage. Very frequent explosions generated ash plumes that rose 850 m and drifted 12 km S and SE. On 13 October a steaming lahar descended the Ceniza (SSW) drainage, carrying blocks up to 2 m in diameter, and branches and tree trunks. During 13-16 October explosions (8-18 per hour) produced ash plumes that rose almost 1 km and drifted 8-12 km S, SW, and W. Ashfall was reported in areas downwind including Sangre de Cristo (8 km WSW), Finca Palo Verde, and Panimaché I and II (8 km SW). Incandescent material was ejected 150-200 m high, causing avalanches of material within the crater, though some of the avalanches traveled long distances, reaching vegetated areas. The lava flow on the W flank was still visible but by 14 October no longer active.

INSIVUMEH reported that during 18-21 August explosions at Fuego generated ash plumes that rose as high as 850 m above the crater and drifted 12 km NW, W, and SW. Incandescent material was ejected 150 m above the crater rim, and caused avalanches of material within the crater area and down drainages on the flanks. According to CONRED, as of 22 August, the number of people confirmed to have died due to the 3 June pyroclastic flows was 169, and 256 remained missing.

INSIVUMEH and CONRED reported relatively quiet conditions at Fuego during 4-9 July characterized mainly by gas emissions and block avalanches on the flanks. During 7-8 July there was about one explosion detected every two hours, producing diffuse ash plumes that rose 500 m above the crater and drifted SW. Block avalanches descended the Seca (W), Cenizas (SSW), and Las Lajas (SE) drainages, while lahars were present in the El Jute (SE), Las Lajas, Cenizas, Taniluyá (SW), Seca, Mineral, and Pantaleón (W) drainages. Seismicity increased on 10 July. Explosions generated ash plumes that rose 2.3 km and drifted 12 km SE, causing ashfall in Morelia (9 km SW) and Panimaché (8 km SW). According to CONRED, as of 4 July, the number of people confirmed to have died due to the 3 June pyroclastic flows was 113, and 332 remained missing.

INSIVUMEH and CONRED reported that 2-7 weak explosions per hour at Fuego generated ash plumes that rose as high as 650 m above the crater rim and drifted W and SW during 27-29 June and 1-3 July. Ashfall was reported on 27 June in areas downwind including Sangre de Cristo and Yepocapa. Avalanches of material descended the S, SW, and W flanks (Santa Teresa, Las Lajas, El Jute, and Cenizas drainages). According to CONRED, as of 3 July, the number of people confirmed to have died due to the 3 June pyroclastic flows was 113, and 197 remained missing. In addition, 12,823 remained evacuated.

INSIVUMEH and CONRED reported that during 20-26 June multiple lahars at Fuego were often hot, steaming, and had a sulfur odor, and were generated from heavy rains and the recent accumulation of pyroclastic-flow deposits from the 3 June events. Lahars remained a significant hazard, and descended the Cenizas (SSW), Las Lajas (SE), Santa Teresa (W), and Taniluyá (SW) drainages. They were 25-45 m wide, as deep as 3 m, and often carried blocks up to 3 m in diameter, tree trunks, and branches. The agencies warned that because the Las Lajas drainage is full of deposits, lahars can continue to descend that drainage or create new channels in San Miguel Los Lotes (one of the hardest-hit areas).

Explosions continued, producing ash plumes that rose as high as 1.3 km above the crater and drifted as far as 15 km in multiple directions. Ashfall was reported in Panimache, Morelia, Sangre de Cristo, and finca Palo Verde on 22 June. Avalanches of material descended the SE, S, and W flanks (Santa Teresa, Las Lajas, and Cenizas drainages). According to CONRED, as of 26 June, the number of people confirmed to have died due to the 3 June pyroclastic flows was 112, and 197 more were missing. In addition, 12,823 remained evacuated.

During 13-19 June INSIVUMEH and CONRED reported that strong lahars at Fuego were often hot, steaming, and had a sulfur odor, and were generated from heavy rains and the recent accumulation of pyroclastic-flow deposits from the 3 June events. Lahars descended the Cenizas (SSW), Las Lajas (SE), Mineral, Santa Teresa (W), El Gobernador, and Taniluyá (SW) drainages. They were 20-45 m wide, as deep as 3 m, and often carried blocks up to 3 m in diameter, tree trunks, and branches. On 14 June lahars disrupted communication in the communities of Morelia (9 km SW), Panimaché I and II (8 km SW), Santa Sofia (12 km SW), El Porvenir (8 km ENE), Yucales, and Sangré de Cristo (8 km WSW), all of Yepocapa (8 km N), and Chimaltenango (21 km NNE), requiring assistance from the Army. Water levels in the Pantaleón River began to rapidly rise in the afternoon of 17 June.

During 16-19 June as many as seven explosions per hour produced ash plumes that rose as high as 1.2 km above the crater and drifted as far as 15 km W, SW, and S. Some explosions were heard in areas within a 10-km radius. Avalanches of material descended the Santa Teresa, Las Lajas, and Cenizas drainages during 17-18 June, producing ash plumes, and ashfall in Panimache, Morelia, Sangre de Cristo, and finca Palo Verde. According to CONRED, as of 19 June, the number of people confirmed to have died due to the 3 June pyroclastic flows remained at 110, and 197 more were missing. In addition, 12,823 people had been evacuated.

During 6-12 June INSIVUMEH and CONRED reported that strong lahars at Fuego were often hot, steaming, and had a sulfur odor, and were generated from heavy rains and the recent accumulation of pyroclastic-flow deposits from the 3 June events. On 6 June lahars descended the Santa Teresa, Mineral, and Taniluyá drainages (tributaries of the Pantaleón river) and possibly the Honda drainage, halting search-and-rescue efforts. The lahars were 30-40 m wide, 2-5 m deep, and carried blocks (2-3 m in diameter) and tree parts. CONRED noted on 9 June that deposits on roads were being cleaned at a rate of 150 m per day, and that exposed deposits were as hot as 150 degrees Celsius. Significant hot lahars, 40 m wide and 5 m deep, traveled down the Seca, Mineral, Niágara, and Taniluyá drainages, carrying rocks and tree branches. On 10 June a strong lahar traveled down the Seca, Mineral, Niagara, Taniluyá, and Ceniza drainages. It was 35 m wide, 3 m deep, and carried blocks up to 1 m in diameter, tree trunks, and branches. Lahars that traveled down the Seca and Mineral drainages on 11 June were 40 m wide and 3 m deep. Lahars on 12 June were 20-45 m wide and 2-5 m deep, and flowed down the Ceniza and Mineral rivers.

During 6-11 June as many as nine weak explosions per hour produced ash plumes that rose as high as 1.1 km above the crater and drifted 8-15 km W, SW, and S. Avalanches of material descended the Las Lajas and Santa Teresa ravines. Some explosions vibrated local structures. At 0820 on 8 June a pyroclastic flow descended the Las Lajas and El Jute drainages, producing an ash plume that rose as high as 6 km and drifted W and SW. Explosive activity increased during 11-12 June, with dense ash plumes rising 1.3 km and drifting as far as 25 km N and NE. Pyroclastic flows traveled down the Seca drainage. According to CONRED, as of 12 June, the number of people that had died due to the 3 June pyroclastic flows was 110, and 197 more were missing. In addition, 12,578 people had been evacuated.

According to Simon Carn, satellite data analysis showed that the event produced the highest SO2 loading measured from a Fuego eruption in the satellite era (since 1978), and therefore most likely the highest since the major 1974 eruption. He went on to note that the SO2 mass was about ~2 orders of magnitude than the 1974 eruption, which had a significant stratospheric impact.

At 1650 INSIVUMEH noted reports of lahars descending the Pantaleón drainage (fed by the Santa Teresa and El Mineral rivers) and other drainages. CONRED had evacuated communities near Fuego, including Sangre de Cristo, finca Palo Verde, and Panimache. At 2200 (~16.5 hours after the increased activity began), the eruption waned, with activity characterized by weak-to-moderate explosions, crater incandescence, and ash plumes that rose almost 800 m. The seismic station (FG3) recorded the last pyroclastic flow at 1845. By 0725 on 4 June seismicity had returned to normal levels. Explosions occurring at a rate of 5-7 per hour produced ash-rich plumes that rose as high as 900 m and drifted 15 km SW, W, NW, and N. Avalanches of material descended the flanks. The La Aurora International Airport reopened and flights resumed at 0930.

On 5 June INSIVUMEH reported that activity again increased. Explosions occurring at a rate of 8-10/hour, some strong, generated ash plumes that rose 5 km and drifted E and NE. At 1928 a pyroclastic flow traveled down the Las Lajas drainage. News articles noted that authorities called for another evacuation.

CONRED reported that by 0630 on 6 June a total of 12,089 people had been evacuated, with 3,319 people dispersed in 13 shelters. One bridge and two power networks had been destroyed. According to news sources on 6 June, Guatemala's National Institute of Forensic Sciences stated that 75 people were confirmed to have died and 192 were still missing. Many, possibly thousands, received burns and other injuries. Weather conditions, continuing activity at Fuego, poor air quality, hot pyroclastic flow deposits, and rain made rescue efforts difficult.

INSIVUMEH reported that beginning at 1400 on 17 May a lahar descended the Seca (Santa Teresa) drainage on Fuego’s W flank. The lahar was 25 m wide, 1 m deep, and carried trees and blocks 1.5 m in diameter. During 19-21 May explosions occurred at a rate of 5-8 per hour, and generated ash plumes that rose almost 1 km and drifted 10-20 km S, SW, and W. Some explosions were accompanied by rumbling audible more than 30 km away, and shock waves that vibrated structures in Morelia (9 km SW) and Panimaché (8 km SW). Incandescent material was ejected 200-300 m above the crater rim, and generated avalanches of material within the Seca, Ceniza (SSW), and Las Lajas (SE) drainages that reached vegetated areas. Ash fell in areas downwind including in Santa Sofía (12 km SW), Morelia, Panimaché I and II, and Finca Palo Verde. A lava flow 700-800 m long was active in the Ceniza drainage.

Small ash explosions at Fuego on 11 and 12 May rose to 5 km (15,000 ft) a.s.l., or approximately 1 km (3,280 ft) above the summit. The ash dispersed quickly to the southwest and was visible on webcams.

Activity increased on 14 April and remained elevated through 17 April. Moderate-to-strong explosions were detected at a rate of 6-9 per hour, and sometimes produced shock waves that vibrated houses in Morelia and Panimaché. Dense ash plumes rose as high as 1.1 km and drifted 20 km W and S, though winds also carried the ash to higher altitudes to the SE. Incandescent material was ejected as high as 300 m above the crater rim, and generated avalanches of material in the crater area. Ashfall was reported in areas downwind including in Santa Sofía, Morelia, Panimaché I and II, El Porvenir, and Finca Palo Verde. The rate of explosions increased to 7-10 per hour on 16 April; explosions sometimes caused structures in Panimache, Morelia, La Reina, and Alotenango (8 km ENE) to vibrate. A lava flow traveled 1.3 km down the Seca drainage.

INSIVUMEH reported that explosions at Fuego during 7-13 February generated ash plumes that rose as high as 1.5 km and drifted 10-12 km N, NW, SW, and S. Avalanches of material traveled down the Seca (W), Ceniza (SSW), and Taniluyá (SW) drainages on 12 February, and down the Las Lajas (SE) and Honda (E) drainages on 13 February. Ash fell in areas downwind on 13 February including Morelia (9 km SW) and Panimaché (8 km SW).

On 2 February there were 3-5 weak explosion recorded per hour, with ash plumes rising 750 m and drifting 5-8 km W, SW, and S. Shock waves and rumbling were noted, and the lava flows remained visible. During 4-5 February ash plumes from explosions (about 5 per hour) produced ash plumes that rose 700 m and drifted W and SW. Incandescent material was ejected 200 m above the crater, causing weak avalanches of material around the crater area and in some vegetated areas.

INSIVUMEH reported that the 12th effusive/explosive eruption at Fuego in 2017 began on 10 December and, based on seismicity, lasted for about 36 hours. Ash plumes from moderate-to-strong explosions rose as high as 1.2 km above the crater rim and drifted 20 km S and SW. Lava flowed as far as 1.5 km W down the Seca (Santa Teresa), SW down the Taniluyá, and SSW down the Ceniza ravines. Ash fell in the communities of La Rochela, San Andrés Osuna, Morelia (9 km SW), and Panimaché I and II (8 km SW). On 12 December there was an average of 10 explosions per hour, generating avalanches in the Ceniza and Taniluyá drainages and ashfall in nearby areas.

INSIVUMEH reported that during 2-3 November tremor at Fuego increased. Explosions (6-8 per hour) generated ash plumes that rose as high as 1.3 km above the crater and drifted 15 km W and SW. During 4-5 November there were 5-8 explosions per hour producing ash plumes that rose 1.2 km and drifted 10-15 km W and SW. Incandescent material was ejected 300 m above the crater, causing avalanches that were confined to the crater. The 11th effusive eruption phase in 2017 began on 5 November. Lava flowed 1-1.2 km W down the Seca drainage and 800 m SSW down the Ceniza drainage. Avalanches of material from the ends of the lava flows descended the flanks and reached vegetated areas. About 6-8 explosions per hour generated ash plumes that rose as high as 1.1 km and drifted 10-15 km W and SW. Ashfall was reported in areas downwind including Panimaché I and II (8 km SW), Santa Sofía (12 km SW), Morelia (9 km SW), and El Porvenir. The effusive phase ended on 7 November.

INSIVUMEH reported that on 25 August lahars descended the Pantaleón, Cenizas, El Jute, and Las Lajas drainages on Fuego’s W, SSW, and SE flanks. The lahar in the Pantaleón river (fed by the Santa Teresa and El Mineral rivers) was 35 m wide, 2.5-3 m deep, and carried trees and blocks more than 2-3 m in diameter. The Cenizas river lahar was about 25 m wide, 3 m deep, and carried blocks up to 2 m in diameter. The lahars in El Jute and Las Lajas drainages were 20 m wide, 1.5 m deep, and carried tree debris and blocks up to 2 m in diameter. Explosions during 26-29 August generated ash plumes that rose as high as 950 m above the crater and drifted 7-12 km SW, W, and NW. Incandescent material was ejected 100-200 m above the crater rim, and caused avalanches of material around the crater area. Explosions were audible within a 20-km radius, and shock waves vibrated local structures. Ash fell in areas downwind including Panimache I and II, Morelia, Finca Palo verde, Sangre de Cristo, and El Porvenir. On 29 August lahars 10 m wide and 1.5 m deep descended the Santa Teresa and El Mineral drainages, carrying tree debris and blocks up to 2 m in diameter.

INSIVUMEH reported that multiple explosions at Fuego during 13-14 July generated ash plumes that rose as high as 950 m above the crater and drifted 8-10 km NW and W. Incandescent material was ejected 100 m above the crater rim, and caused avalanches of material that traveled down the Ceniza (SSW), Taniluyá (SW), and Trinidad (S) drainages. On 16 July a 30-m-wide, 2-m-deep, hot lahar descended tributaries of the Pantaleón (W) drainage, carrying blocks more than 2 m in diameter, branches, and tree trunks. The lahars again overtook the road between communities on the SW flank, isolating the village of Sangre de Cristo (8 km WSW) and the Palo Verde estate. Vulcanian explosions during 17-18 July produced dense ash plumes that rose almost 1 km above the crater rim and drifted 15 km W and NW. Ash fell in Panimache (8 km SW), Morelia (9 km SW), and Santa Sofía (12 km SW).

INSIVUMEH reported that during 8-9 June explosions at Fuego generated ash plumes that rose as high as 1.1 km above the crater rim and drifted 15 km W, NW, and N. Rumbling was noted, and block avalanches descended multiple ravines. Lahars traveled down several ravines on the SE, S, and SW flanks, especially down the Pantaleón (W) ravine. On 10 June at 1150 a lahar descended the Ceniza (SSW) drainage, carrying blocks 1 m in diameter. The lahar was 15-18 m wide and as deep as 3 m. During 10-11 June explosions produced ash plumes that rose 750-1,050 m and drifted 12-15 km W, NW, and N. Shock waves from some of the explosions were detected. Two hot lahars descended the flanks on 13 June. The first one traveled down the Pantaleón river and was 35 m wide and 2.5-3 m deep, and carried trees and blocks 2-3 m in diameter. The second lahar descended the Ceniza and was 25 m wide and 3 m deep, and carried blocks up to 2 m in diameter.

INSIVUMEH reported increased activity at Fuego on 1 June, characterized by an increase in the number of explosions (6-7 per hour) and ash plumes rising as high as 950 m above the crater and drifting W. Explosions generated shock waves that rattled structures in multiple areas including Panimaché I and II (8 km SW), Morelia (9 km SW), Santa Sofía (12 km SW), El Porvenir, and Sangre de Cristo (8 km WSW). Incandescent material was ejected as high as 500 m above the crater rim, and caused avalanches of material on the flanks. On 2 June explosions produced ash plumes that rose 550-950 m and drifted 10-12 km W and SW. Shock waves were detected within a radius of 25 km. Incandescent material was ejected 300-500 m high, causing avalanches in the Ceniza (SSW), Taniluyá (SW), and Santa Teresa (W) drainages. During 3-4 June there were 2-4 explosions recorded per hour. Ash plumes rose 650-1,050 m high and drifted 8-10 km W and SW. Weak shock waves rattled nearby buildings. Avalanches from ejected incandescent material continued to descend the three drainages. On 4 June a hot lahar descended the Pantaleón (W) drainage, carrying blocks more than 2 m in diameter, branches, and tree trunks. The lahar was 30 m wide and had a strong sulfur odor. During 4-5 June incandescent material rose 150 m and a lava flow traveled 300 m down the Santa Teresa drainage. On 6 June INSIVUMEH noted that eruptive episode number five had ended, with remnant lava flows in the Santa Teresa (2 km long) and Ceniza (3 km long) drainage. Explosions generated ash plumes that rose 950 m and drifted 15 km W and NW.

INSIVUMEH reported that on 23 May a hot lahar descended Fuego’s Santa Teresa (W) drainage, carrying blocks 2 m in diameter, branches, and tree trunks. The lahar was 10 m wide and 1 m high, and could be heard in the vicinity of the drainage. On 27 May a large hot lahar traveled down the Santa Teresa drainage, carrying blocks 2 m in diameter, branches, and tree trunks. The lahar was 30 m wide, 2 m high, and had a strong sulfur odor.

During 24-25 and 27-30 May explosions generated ash plumes that rose as high as 950 m above the crater rim and drifted as far as 12 km W and SW. Ash fell in multiple areas including Panimaché I and II (8 km SW), Morelia (9 km SW), Santa Sofía (12 km SW), Los Yucales, El Porvenir, and Sangre de Cristo (8 km WSW). Incandescent material was ejected as high as 250 m above the crater rim, and caused avalanches of material that traveled into the Ceniza (SSW), Taniluyá (SW), and Santa Teresa drainages.

In a special report INSIVUMEH reported that a new phase of activity (the fourth of the year) at Fuego began on 5 May and was the strongest activity recorded since 2012. Strong explosions, sometimes producing shock waves, generated dense ash plumes that rose 1.3 km above the crater and drifted more than 50 km S, SW, and W. Ashfall was reported in many areas downwind, including San Pedro Yepocapa (8 km N), Morelia (9 km SW), Santa Sofía (12 km SW), El Porvenir (8 km ENE), finca Palo Verde, Santa Lucia Cotzumalguapa (23 km SW), Siquinala, San Andrés Osuna, Chuchu, and La Reunión. Lava flows traveled 2 km down the Santa Teresa (W) drainage and 3 km down the Las Lajas drainage. Pyroclastic flows descended the Trinidad (S), Las Lajas (SE), Ceniza (S), and Santa Teresa drainages. Residents of Sangre de Cristo (8 km WSW) were evacuated. Explosions were not reported that next day and the lava flows may have stopped advancing. According to a news article, about 300 people had been evacuated from Panimache (8 km SW). During 7-8 May lower-energy explosions generated ash plumes that rose as high as 750 m above the crater and drifted 8-20 km W and SW. Gases were observed rising from pyroclastic flow deposits in the ravines.

INSIVUMEH reported that beginning at 1700 on 24 April a hot lahar descended Fuego’s Río Ceniza (SSW) drainage, carrying blocks 2 m in diameter, branches, and tree trunks. The lahar was heard up to 1 km away. During 29 April-2 May explosions generated ash plumes that rose as high as 1.1 km above the crater rim and drifted as far as15 km W and SW. Some of the explosions produced shock waves felt within a 10-km radius. Ash fell in Sangre de Cristo (8 km WSW) and possibly other areas. Incandescent material was ejected as high as 200 m above the crater rim.

INSIVUMEH reported that during 6-11 April explosions at Fuego generated ash plumes that rose as high as 850 m above the crater rim and drifted as far as11 km W, SW, and S. Ashfall was reported in areas downwind including Panimaché I and II (8 km SW), Morelia (9 km SW), and Santa Sofía (12 km SW). Rumbling from the explosions was sometimes heard. During 10-11 April incandescent material was ejected 100-150 m above the crater, generating minor avalanches in the area of the cone.

INSIVUMEH reported that activity at Fuego increased on 1 April, with the beginning of a new effusive eruption, the third one in 2017. Explosions occurring an average of 10 per hour generated shock waves that vibrated local structures. An ash plume rose an estimated 1.3 km and drifted 10 km W, SW, and S; weather clouds hindered observations. Later that day lava fountains rose 100-300 m high and fed lava flows that traveled 400 m down the Trinidad (S) and Las Lajas (SE) drainages. The effusive phase lasted about 16 hours, ending on 2 April, with lava flows stopping as far as 3 km, and expanding into the Santa Teresa (W) drainage. Ash plumes drifted as far as 80 km W, causing ashfall in areas downwind including Atitlan Lake, Chicacao, Mazatenango, Retalhuleu, and El Palmar. On 4 April explosions generated ash plumes that rose 750 km and drifted S, and avalanches pf material descended the Ceniza drainage.

INSIVUMEH reported that during 25-28 March explosions at Fuego generated ash plumes that rose as high as 1.1 km above the crater rim and drifted 10-12 km SW and S. Ashfall was reported in areas downwind including Panimaché I and II (8 km SW), Morelia (9 km SW), Santa Sofía (12 km SW), Los Yucales, and El Porvenir. Shock waves and rumbling from the explosions were sometimes heard; structures in local areas were rattled from explosions during 26-27 March. Incandescent material was ejected as high as 300 m above the crater rim, and sometimes landed 250 m away. Avalanches of material were confined to the crater. INSIVUMEH noted that activity had become more intense on 27 March.

INSIVUMEH reported that during 16-21 March explosions at Fuego generated sometimes dense ash plumes that rose as high as 950 m above the crater rim and drifted 10-12 km W, SW, and S. Ashfall was reported in Panimaché I and II (8 km SW), Morelia (9 km SW), Santa Sofía (12 km SW), and El Porvenir. Shock waves and rumbling from the explosions were sometimes heard. Incandescent material was ejected as high as 200 m above the crater rim. During 18-19 March incandescent material was ejected 200 m away from the crater. In a special report dated 21 March INSIVUMEH noted that lahars had begun descending the Santa Teresa and Las Lajas drainages at 1623 based on seismic data; it had been raining for a few days.

INSIVUMEH reported that during 21-22 February there were 28 explosions detected at Fuego, and ash plumes that rose as high as 1 km above the crater rim and drifted E and NE. There were 32 explosions recorded during 23-24 February; ash plumes rose 650 m and drifted S and SW. Lava fountains rose 200 m high, and generated a 200-m-long lava flow that descended the Santa Teresa (W) drainage. A second lava flow descended the Las Lajas (SE) drainage. Seismicity increased on 24 February. On 25 February explosions generated ash plumes that rose as high as 1.3 km above the crater and drifted more than 25 km NW, N, NE, and E. Ash fell in Alotenango (8 km ENE), San Vicente Pacaya, El Rodeo, El Zapote, La Reunión, and Alotenango. Lava fountains rose 300 m, and material was ejected as far away as 500 m. The lava flows continued to advance, extending 1.2 km in the Santa Teresa drainage, 1.3 km in the Las Lajas drainage, and 1.6 km in the Ceniza (SSW) drainage. Weak-to-moderate explosions during 26-27 February produced ash plumes that rose at most 750 m and drifted 8 km W and SW.

Based on INSIVUMEH notices, CONRED reported that at 1345 on 25 January a Strombolian phase began at Fuego. Weak-to-moderate explosions generated ash plumes that rose 750 m above the crater rim and drifted 10 km W and SW. Lava fountains rose 200 m above the crater rim and fed lava flows that traveled 1 km SSW down the Ceniza drainage. Avalanches of material advanced more than 300 m down the Ceniza and Trinidad (S) drainages into vegetated areas. Ash fell on the SW and W flanks. The report also noted that a previous Strombolian phase had begun on 3 January.

In a special bulletin from 20 December, INSIVUMEH reported increased activity at Fuego. Moderate to strong explosions which sometimes produced shock waves occurred at a rate of 8-13 per hour, and ash plumes rose as high as 950 m and drifted more than 15 km W, SW, and S. Incandescent material was ejected 200-300 m above the crater and landed 300 m away on the flanks. Avalanches of material descended the flanks. Ashfall was reported in areas downwind including Panimaché (8 km SW), Morelia (9 km SW), Santa Sofía (12 km SW), and Sangre de Cristo (8 km WSW).

INSIVUMEH reported that during 6-7 December the number of explosions at Fuego increased to 3-5 per hour. Ash plumes rose 1 km above the crater and drifted 12 km W and SW, causing ashfall in areas downwind including Morelia (9 km SW), Santa Sofía (12 km SW), Panimaché I and II (8 km SW), El Porvenir (8 km ENE), and San Pedro Yepocapa (8 km N). Incandescent block avalanches reached vegetated areas. Activity continued at the same level through 12 December, although 4-6 explosions per hour were detected during 12-13 December. Ash plumes from explosions during 8-12 December rose as high as 1.1 km and drifted 12-15 km W, SW and S. Ash fell in the same areas downwind. During 8-9 and 11-12 December incandescent material was ejected 200 m above the crater, causing avalanches of material in the crater and towards the main ravines.

INSIVUMEH reported that during 16-17 and 19 November explosions at Fuego generated ash plumes that rose 650-950 m above the crater rim and drifted 12 km W, SW, and S. Incandescent material was ejected as high as 200 m causing minor avalanches confined to the crater. The 15th Strombolian episode in 2016 began on 20 November. Lava fountains rose as high as 300 m and fed three lava flows which traveled 1 km S down the Trinidad drainage, 2 km SSW down the Ceniza drainage, and 2.5 km SE down the Las Lajas drainage. Explosions generated ash plumes that rose as high as 1.3 km and drifted 15 km S and SW. Ashfall was reported in areas downwind including Morelia (9 km SW), Santa Sofía (12 km SW), and Panimaché I and II (8 km SW). Lava fountains continued to rise 300 m above the crater rim on 21 November and avalanches of material descended the Santa Teresa (W) and Taniluyá (SW) drainages. Ash plumes rose 1.3 km and drifted 20 km S, SW, and W, causing ashfall again in Morelia, Santa Sofía, and Panimaché I and II. INSIVUMEH noted that on 22 November the Strombolian eruptive phase had ended. Ash plumes continued to be generated, rising as high as 1.8 km and drifting more than 10 km S and SW.

INSIVUMEH reported that during 11-15 November explosions at Fuego generated ash plumes that rose as high as 1.3 km and drifted more than 15 km W and SW. Some explosions produced shock waves detected within a 10 km radius and also ejected incandescent material as high as 300 m. Minor avalanches were confined to the crater. Ashfall was reported in Morelia (9 km SW), Santa Sofía (12 km SW), Sangre de Cristo (8 km WSW), and Panimaché I and II (8 km SW).

Based on INSIVUMEH reports, CONRED stated that beginning at 0730 on 27 September loud explosions at Fuego generated ash plumes that rose 1 km above the crater rim and drifted more than 15 km W and SW. After about 36 hours of elevated activity, the 13th Strombolian episode in 2016, Fuego returned to more normal levels. On 28 September there were 4-6 explosions per hour recorded, producing ash plumes that rose 550-650 m and drifted 8-12 km W and SW. Lava flows in the Las Lajas (SE) and Santa Teresa (W) drainages had stalled. Explosions during 30 September-1 October and 3-4 October generated ash plumes that rose as high as 1.1 km and drifted 7-13 km W, SW, and S. During 3-4 October explosions produced shock waves and ashfall in Morelia (10 km SW). Incandescent material was ejected 300 m high, and block avalanches reached vegetated areas.

INSIVUMEH reported that during 23-26 September lava fountains rose as high as 200 m above Fuego’s crater rim, and lava flows traveled 3.5 km SE in the Las Lajas drainage. Explosions occurring at a rate of 3-4 per hour produced ash plumes that rose 450-850 m and drifted 8-12 km E, S, SW, and W. On 26 September a 10-m-wide and 1-m-deep lahar, triggered by heavy rain in the area, descended the Santa Teresa (W) drainage, a tributary of the Pantaleón river. The lahar carried blocks 50 cm in diameter, branches, and tree trunks. Moderate to large explosions generated ash plumes that rose 1.2 km and drifted 20 km W and SW. Lava fountains rose 200-300 m and fed two lava flows; the first traveled 1.5 km down the Las Lajas drainage and the second traveled 1.8 km down the Santa Teresa drainage. Avalanches originated from a degassing fissure on the S flank. Ashfall was reported in areas on the W and SW flank, including the Palo Verde finca, Sangre de Cristo (8 km WSW), and Yepocapa (8 km NW).

On 8 September INSIVUMEH reported that the 12th eruptive episode at Fuego in 2016 had ended. Weak explosions produced ash plumes that rose as high as 750 m above the crater and drifted more than 8 km W and SW. Lava fountains rose 100 m above the crater rim; the lava flow in the Las Lajas (SE) drainage was no longer advancing. During 11-13 September explosions produced ash plumes that rose 450-850 m and drifted 6-10 km NW, W, and SW. Explosions ejected incandescent material as high as 150 m above the crater rim.

INSIVUMEH reported that during 4-5 September incandescent material rose as high as 200 m above Fuego’s crater rim, and ash plumes rose 450 m and drifted W and SW. Sounds resembling train engines were constant and rumblings were heard six to nine times per hour. A 500-m-long lava flow was active in the Las Lajas (SE) drainage. Activity increased during the early afternoon on 5 September. The magnitude and number of explosion (6 per hour) increased, generating ash plumes that rose 850 m and drifted 12 km W and SW. The lava flow had grown to 1.2 km long. The rate of six explosion per hour continued on 6 September. Ash plumes rose 850 m and drifted 10 km W and SW, causing ashfall in Sangre de Cristo (8 km WSW), Panimache (8 km SW), and other nearby areas.

INSIVUMEH reported that during 7-10 July there were 6-8 explosions per hour at Fuego, generating ash plumes that rose as high as 950 m above the crater and drifted W and NW. Ash fell in Yepocapa (8 km N), Sangre de Cristo (8 km WSW), Panimache (8 km SW), and other nearby areas. Some explosions generated shock waves, and incandescent material was ejected 150 m high. There were 18 explosions detected during 11-12 July; ash plumes rose as high as 850 m and drifted more than 10 km W and SW.

INSIVUMEH reported that during 30 June-5 July explosions at Fuego generated ash plumes that rose as high as 950 m and drifted W and SW. Some explosions also ejected incandescent material as high as 150 m that then fell onto the flanks and caused minor avalanches. In a special bulletin posted on 5 July, INSIVUMEH noted that 18 explosions were registered within a 24-hour period. Ash plumes rose as high as 1 km and drifted W and SW.

INSIVUMEH reported that during 23-24 June explosions at Fuego occurred at a rate of 2-5 per hour, and generated ash plumes that rose 650-950 m above the crater and drifted 10 km SW, W, NW, and N. Lava fountains rose as high as 200 m above the crater, and fed a lava flow that traveled 600 m SE down the Las Lajas (SE) drainage.

In a special bulletin from 1200 on 26 June, INSIVUMEH stated that the tenth episode of effusive activity at Fuego had ended, having lasted for a period of over 30 hours. The report noted that weak explosions continued, producing ash plumes that rose as high as 850 m and drifted 10 km S, SW, and W. Lava flows had advanced to 600 and 800 m in the El Jute (SE) and Las Lajas drainages, respectively. Explosions during 26-28 June generated ash plumes that rose 550-850 m and drifted SSW. Weak shock waves from explosions were detected during 26-27 June, and abundant crater incandescence was visible during 27-28 June.

On 19 May CONRED reported that pyroclastic flows not generated by explosions had descended Fuego's flanks during the previous 12 hours. INSIVUMEH reported that during 19-22 May weak-to-moderate explosions generated ahs plumes that rose 450-750 m above the crater and drifted 7 km W, SW, and S. Incandescent material was ejected 100 m high and generated avalanches down the Las Lajas (SE), Trinidad (S), Santa Teresa (W), Ceniza (SSW), and Honda drainages. A 300-m-long lava flow was active in the Las Lajas drainage. CONRED noted that at 1800 on 22 May Fuego began its 10th Strombolian phase for 2016, characterized by a 1.5-km-long lava flow, explosions, and ash plumes that rose 1.3 km above the crater and drifted 15 km W and SW. During 23-24 May explosions produced ash plumes that rose 4.3-4.8 km and drifted 10-15 km WSW. The lava flow was active as far as 1 km.

In a special bulletin from 7 April, INSIVUMEH reported that moderate and strong explosions at Fuego generated ash plumes that rose 850-1,050 m and drifted 15 km SW. The explosions were heard in areas as far as 20 km away, and were accompanied by shock waves that vibrated structures within a 12-km radius. Rumbling was heard in Santa Lucia Cotzulmaguapa (20 km SW). Ash fell in local areas including Panimache and Panimache II (8 km SW), Morelia (9 km SW), and Sangre de Cristo (8 km WSW). During 7-8 April gray ash plumes from explosions rose as high as 950 m and drifted 15 km W and SW. Rumbling noises and detectable shock waves continued. Incandescent material was ejected 250 m high and generated avalanches down the Las Lajas (SE), Trinidad (S), Santa Teresa (W), and Taniluyá (SW) drainages. A high level of activity continued during 9-12 April; five to six explosions per hour were detected during 9-10 April. Dense ash plumes rose over 1 km high and drifted 15 km SW. Ashfall was noted in multiple villages including San Pedro Yepocapa (8 km N), Panimaché, and Sangre de Cristo. Shock waves vibrated structures within 15 km, and rumbling was heard 30 km away. At night block avalanches were seen reaching vegetated areas on the flanks. During 11-12 April incandescent material was ejected 200 m high, causing avalanches down the Las Lajas, Trinidad, Santa Teresa, Taniluyá, and Ceniza (SSW) drainages.

INSIVUMEH reported that during 24-25 and 27-29 March explosions at Fuego generated ash plumes that rose 550-950 m above the crater and drifted 6-12 km SE, S, SW, and W. Incandescent material was ejected 200 m high on 25 March, producing avalanches within the crater and down the Trinidad (S), Ceniza (SSW), and Taniluyá (SW) drainages. On 29 March ashfall was reported Sangre de Cristo (8 km WSW) and Panimaché I and II (8 km SW).

In a special report from 21 March INSIVUMEH reported a change in the eruptive pattern at Fuego. Explosions generated ash plumes that rose 550-950 m above the crater and drifted 12 km E. Ashfall was reported in Sangre de Cristo and Panimaché I and II. Explosions continued the next day. Ash plumes rose as high as 950 m and drifted S and SW. Incandescent material was ejected 300-400 m high, causing avalanches in the crater.

On 10 March INSIVUMEH reported a new phase of activity at Fuego characterized by Vulcanian explosions, and ash plumes that rose 650 m and drifted E. Strong shock waves and rumbling sounds were detected 10 km away. During 10-11 March explosions generated ash plumes that rose 650-950 m and drifted E and NE. Incandescent material was ejected as high as 200 m and caused avalanches in the Trinidad (S) and Taniluyá (SW) drainages. Cloud cover prevented visual observations during 12-13 March; shock waves were detected. During 14-15 March explosions produced ash plumes that rose 450-750 m and drifted 8-10 km SW, W, and NW. Incandescent material was ejected as high as 150 m.

INSIVUMEH noted that the fourth episode of effusive activity at Fuego for 2016 had begun on 29 February and lasted for about 48 hours. At the beginning of the episode, ash plumes rose as high as 1.3 km and drifted 15 km S and SW, and lava fountains rose 100-150 m above the crater. In a special report on 2 March, INSIVUMEH noted that explosions persisted even though seismicity had declined. Explosions, detected 25 km away, produced ash plumes that rose 2.3 km above the crater and drifted 40 km W and NW. Ash fell in Sangre de Cristo, Morelia, Panimaché I and II, and Yepocapa. A 3-km-long lava flow advanced in the Honda ravine. Later that day, at 1930, INSIVUMEH stated that the effusive episode had ended. Weak explosions generated ash plumes that rose 750 m and drifted 10 km WNW. During 3 and 5-6 March explosions continued, producing ash plumes that rose as high as 550 m and drifted 8-10 km W, SW, and SE.

In a special report, INSIVUMEH noted that the third episode of effusive activity at Fuego for 2016 had ended at 1830 on 10 February. Afterward some minor explosions generated ash plumes that rose 450 m above the crater and drifted 10 km NNE. Lava flows had traveled 3 km down the Las Lajas drainage (SE) and in the Trinidad drainage (S). During 11-16 February explosions generated ash plumes that rose 350-550 m and drifted almost 11 km W, SW, S, and SE.

On 16 December INSIVUMEH reported that activity at Fuego decreased, although lava flows remained active in the Las Lajas (SE), Trinidad (S), and Santa Teresa (SW) drainages. Ash plumes from weak explosions drifted 15 km SW, S, and SE. During 16-17 December there were 4-5 explosions per hour, generating ash plumes that rose 650-750 m above the crater and drifted 8-12 km W and SW. Explosions during 20-22 December produced ash plumes that rose 550-950 m and drifted 8-10 km W. Incandescent material was ejected 150 m high, landed on the flanks, and then formed small avalanches in the Santa Teresa (SW), Taniluyá (SW), Trinidad, and Ceniza drainages.

INSIVUMEH reported that during 10-12 December explosions at Fuego generated ash plumes that rose 450-950 m above the crater and drifted as far as 12 km W and SW. Shock waves from the explosions vibrated nearby homes. Incandescent material was ejected 200 m high, landed on the flanks, and then formed small avalanches in the Santa Teresa (SW), Taniluyá (SW), and Las Lajas (SE) drainages. Block avalanches reached vegetated areas during 11-12 December. Activity increased during the night of 14-15 December, characterized by an increased number of explosions (4-6 per hour). Ash plumes rose almost 1 km high and drifted 10-15 km NE, E, and SE. Two 800-m-long lava flows were active in the Trinidad (S) and Santa Teresa drainages.

INSIVUMEH reported that by 8 October the lava flows on Fuego’s flanks were 800 m and 1.5 km long, and advancing into the Santa Teresa (W) and Trinidad (S) drainages, respectively. Ash plumes from explosions rose 750 m above the crater and drifted 12 km W and SW. Ashfall was reported in Morelia, Sangre de Cristo, Panimache, and Santa Sofía. On 10 October at 2100 activity became constant; incandescent material was ejected 200 m high. Strombolian activity during 12-13 October continued to feed lava flows on the flanks; flows had advanced to 1 and 1.3 km away from the crater in the Santa Teresa and Trinidad drainages, respectively. Explosions, some producing shock waves, continued to generate ash plumes that rose as high as 750 m above the crater and drifted 12 km SW. Ashfall was again reported in Morelia, Sangre de Cristo, Panimache, and Santa Sofía.

INSIVUMEH reported that during 30 September-1 October explosions at Fuego occurred at a rate of 4-6 per hour, generating ash plumes that rose 950 m above the crater and drifted 10 km W. Some explosions produced shock waves. Ash fell in Sangre de Cristo and possibly in San Pedro Yepocapa. During 3-6 October ash plumes from explosions rose 450 m and drifted 10 km W and SW. Shock waves vibrated local structures. Incandescent material was ejected 150 m high, and avalanches descended the Trinidad (S) and Santa Teresa (W) drainages. Advancing lava flows in those same two drainages were 400-600 m long. Ashfall was reported in Panimache I and II, Santa Sofía, and Morelia. In a special report from 7 October, INSIVUMEH noted that activity at Fuego had been at a high level during recent weeks. The lava flows continued to advance; the flows were 1 km long and 700 m long in the Trinidad and Santa Teresa drainages, respectfully. Gas-and-ash plumes rose over 1 km and drifted 12 km W and SW.

Based on INSIVUMEH notices, CONRED reported that for a 30-hour period during 30 June-1 July activity at Fuego was at a high level, characterized by explosions, high-temperature pyroclastic flows (that began on 1 July), and ashfall. Ash plumes rose 4.8 km above the crater and drifted 25 km W and NW, producing ashfall in 22 local communities. The majority of material deposited by pyroclastic flows was in the Las Lajas drainage. Activity decreased later that day. During 4-6 July, INSIVUMEH reported that explosions produced ash plumes that rose as high as 800 m above the crater and drifted 8-10 km SW and W. Incandescent material was ejected 100 m high, and avalanches descended the Santa Teresa and other nearby drainages.

In a special report from 28 June at 2100, INSIVUMEH reported that activity at Fuego had been changing during the previous few hours, characterized by 4-5 explosions per hour and ash plumes rising 850 m. During 28-30 June ash plumes drifted W, causing ashfall in areas downwind. Shock waves from the explosions vibrated structures in areas including Panimache and Panimache II (8 km SW), Morelia (9 km SW), Santa Sofía (12 km SW), and Sangre de Cristo (8 km WSW). Block avalanches descended the flanks. Rumbling was audible as far as 25 km away. During 29-30 June a 300-m-long lava flow was visible in the Las Lajas drainage on the SE flank.

INSIVUMEH reported that during 4-5 June Strombolian activity at Fuego ejected incandescent material 300 m above the crater. Gray plumes rose 1.1 km and drifted 14 km S and SW; ashfall was reported in communities within 11 km, including Panimaché l and ll, Morelia, Sangre de Cristo, and areas in Yepocapa. Lava flows traveled 600 and 1,200 m down the Santa Teresa and Trinidad drainages, respectively. Avalanches of material from the lava-flow fronts descended the drainages. In a special report from 6 June, INSIVUMEH noted that after 30 hours the period of Strombolian activity had ended. Three lava flows, 600, 700, and 1,300 m in length, were no longer active. The report noted that this episode was the fourth for the year. Deformation to the crater had occurred, with two cinder cones visible from several areas. During 6-7 June white plumes rose 150 m and drifted 10 km S and SW. Pulses of incandescence rose 100 m. Explosions during 7-8 June produced ash plumes that rose 750 m and drifted W and S. Ashfall was recorded in areas within a distance of 10 km.

INSIVUMEH reported that during 14-15 May the number and intensity of explosions at Fuego was high. During 14-17 May ash plumes rose 450-750 m above the crater and drifted 10-12 km W and SW. Shock waves from some explosions rattled nearby houses on the W and SW flanks, including in Morelia, Panimache, and Sangre de Cristo. Ashfall was reported in Panimache, Morelia, and Santa Sofía. Incandescent tephra was ejected 150-200 m above the crater and block avalanches descended multiple drainages. In a special report from 18 May, INSIVUMEH stated that hours after of an effusive eruption that ended at 1730 observers noted ash plumes drifting 10 km and a S-flank lava flow. The report also stated that inclement weather had hindered views during the previous few days. During 18-19 May explosions generated ash plumes that rose 550-750 m and drifted 10 km W and SW. Ash fell in Morelia, Panimache I and II, and Santa Sofía. Incandescent tephra was ejected 150 m above the crater and block avalanches descended multiple drainages.

INSIVUMEH reported that during 15-17 April explosions at Fuego generated ash plumes that rose 650-850 m above the crater and drifted 8-11 km S, SW, and W. Incandescent tephra was ejected 150-200 m above the crater. Avalanches originated from the end of a 300-m-long lava flow in the Trinidad drainage. In a special report from 18 April INSIVUMEH noted that lava effusion had ended at 1730 that day. The activity that followed was characterized by explosions occurring at a rate of 2-4 per hour and crater incandescence. During 19-20 April explosions occurring at a rate of 2-3 per hour generated ash plumes that rose 450-750 m and drifted 4-6 km W and NW. Incandescent tephra was ejected 100 m high and avalanches descended the Ceniza and Trinidad drainages. Explosions during 20-21 April produced ash plumes that rose 550 m and drifted 7 km W and NW. Incandescent tephra was again ejected 100 m high.

In a special notice, INSIVUMEH reported that an effusive eruption at Fuego that began on 28 February produced 300-400-m-high lava fountains. One lava flow traveled 1.6 km S down the Trinidad drainage and another traveled 600 m W down the Santa Teresa drainage. The eruption produced rumbling and train sounds audible up to 12 km away. Ash plumes rose 850-1,250 m above the crater and drifted 35 km W. Ashfall was reported in nearby areas including Panimache (8 km SW), Morelia (9 km SW), and Santa Sofía (12 km SW). During 28 February-1 March explosions generated ash plumes that rose an average of 650 m and drifted 9-10 km W. Incandescent material was ejected 150 m above the crater, and a small lava flow (400 m long) descended the Trinidad drainage. INSIVUMEH noted that the effusive phase had ended at 2156 on 1 March. Ash plumes from explosions rose 550-750 m and drifted 10 km W on 2 March and SW on 3 March.

On 12 February INSIVUMEH reported that explosions from Fuego produced water vapor, gas, and ash plumes that rose 350-800 m above the crater and drifted E and S, and at times NW, drifting as high as 1.7 km. During 12-14 February explosions generated ash plumes that rose 800 m and drifted 10-11 km E and SE. Incandescent material was ejected 100-150 m above the crater, causing avalanches in the Trinidad (S) drainage. During 15-16 February block avalanches descended the Cenizas (SSW), Trinidad, and Las Lajas (SE) drainages. Ashfall was reported in Panimache (8 km SW), Sangre de Cristo (8 km WSW), San Pedro Yepocapa (8 km NW). In a special report on 16 February INSIVUMEH noted 4-6 explosions per hour, and ash plumes that rose, based on pilot reports, to altitudes of 7-9.1 km (23,000-30,000 ft) a.s.l. and drifted more than 15 km SW and W. Another special report issued on 17 February stated that 4-6 explosions per hour continued to be detected. Large amounts of ash formed mushroom-shaped clouds that rose 0.6-1.1 km above the crater and drifted over 15 km NW, W, SE, and S. Incandescent material was ejected 150 m above the crater, causing avalanches in the Trinidad, Ceniza, Las Lajas, and Santa Teresa drainages.

In a special bulletin issued on 10 December, INSIVUMEH reported that during the previous few weeks activity at Fuego had remained high, characterized by ash emissions, frequent powerful explosions, and rumbling. On 10 December activity changed, with explosions being accompanied by lava fountains that rose 100-150 m above the crater. During 11-16 December explosions generated ash plumes that rose 650-850 m and drifted 15 km W, SW, S, and SE. Avalanches from lava flows descended drainages. Ashfall was reported in areas near the observatory, and in Morelia (9 km SW) and Panimaché (8 km SW). Incandescent material was ejected 100 m above the crater and explosions sometimes generated shock waves.

INSIVUMEH reported that during 28-30 November explosions at Fuego produced ash plumes that rose at most 1.2 km above the crater and drifted as far as 25 km S, SW, and W. Shock waves from some of the explosions rattled structures near the volcano. Incandescent material was ejected 100-150 m above the crater duirng 29-30 November. Ashfall was reported in Panimaché I and II (8 km SW), Morelia (9 km SW), Santa Sofía (12 km SW), and surrounding communities.

In a special bulletin issued on 1 December, INSIVUMEH reported that activity remained similar to the previous few days, characterized by periods of more frequent and intense explosions observed 6-8 times per hour. Dense gray ash plumes rose almost 1.3 km and drifted 20 km W and SW. Ash fell in Morelia, Santa Sofía, Panimaché, and Yepocapa. Some explosions were audible up to 30 km away. Shock waves vibrated structures on the S and SW flanks. Incandescent blocks descended multiple drainages. During 1-2 December explosions generated ash plumes that rose 850 m and drifted 15 km S and SW.

On 2 September INSIVUMEH seismically detected a lahar flowing through Fuego’s Taniluyá drainage (SW flank). Observations determined a width of 75 m and height of 2.5 m. The flow cut the road between Santa Lucia Cotzulmaguapa and the communities of Morelia, Santa Sofía, and Panimaché I and II. Lahars were also detected within Río Ceniza (SSW) and Santa Teresa (W).

During 13-19 August, INSIVUMEH reported weak to moderate explosions at Fuego with incandescent blocks being expelled 500-800 m above the crater, activity accompanied on 14 and 16 August by white plumes that rose 200-300 m above the crater and drifted W. On 13 and 15 August INSIVUMEH reported rumbling from shock waves that rattled structures up to 8 km from the volcano in the villages of Panimaché I and II, Morelia, and others in this area, and on 17 August jet engine like sounds lasting 1-4 minutes. On most days incandescent blocks were expelled 50-400 m above the crater, and weak to moderate avalanches of blocks were channeled into the Las Lajas (SE), Trinidad (S), Ceniza (SSW), Taniluyá (SW), Santa Teresa and Barranca Honda canyons. Ash plumes rose 4.2-4.5 km (13,800-14,800 ft) a.s.l. and drifted 8-15 km W and SW. Ashfall was reported in Morelia (9 km SW), Panimaché (8 km SW), Panimaché II, Sangre de Cristo (8 km WSW), Yepocapa (8 km WNW), and Hagia Sophia. On 18 August the Washington VAAC reported several discrete ash emissions based on satellite and wind data.

During 16-22 July, INSIVUMEH reported moderate to strong explosions at Fuego with incandescent blocks being expelled 200-500 m above the crater. On July 22 the explosions also ejected gray ash. Most days weak avalanches moved down the flanks. Light gray eruption columns reported on 16 July rose 4-4.5 km (13,100-14,800 ft) a.s.l. and drifted 7-10 km W, SW, WSW, E, and NE. Weak white fumarolic plume rose 200-300 m above Fuego’s summit crater. A special bulletin on 18 July noted an increased number of explosions and a change in the eruptive pattern. Rumbling and jetting sounds often accompanied moderate to strong explosions that produced shock waves 12-15 km away and rattled structures in Panimache and Morelia on the flanks.

During 30 June-14 July, INSIVUMEH frequently reported a white fumarolic plume rising from Fuego’s summit extending up to 4,000 m (13,123 ft) a.s.l.. Weak-to-moderate explosions generated ash plumes to similar heights during 30 June and 1, 4, 6, 7, and 9-13 July. Rumbling and jetting sounds often accompanied these explosions, often with durations of 1-5 minutes. Pulses of incandescence reached 50-100 m above the rim on 30 June, and 6, 7, and 12 July. Remobilized ash reduced visibility on 4, 9, and 10 July. Surges of lava and incandescent avalanches traveled from the summit down the flanks on 1 July (~150 m into the Trinidad drainage), 6 July (100 m into Taniluya and 200 m into the Ceniza), 11 July (~100 m into Taniluya), 12 July (Santa Teresa, Taniluya, Ceniza, Trinidad, Las Lajas, and Honda), and 13 July (~400 m into the Ceniza).

INSIVUMEH reported that on 25-29 June weak to moderate explosions generated ash plumes that rose 500-800 m above the crater and drifted 10-12 km W, NW, and SE. Incandescent material that was ejected 100-200 m above the crater landed on the flank and formed avalanches. A lava flow from the crater moving SW towards the Tanilaya drainage generated avalanches into the Ceniza drainage (SSW). On 26 June explosions generated moderate and strong acoustic waves that sounded like a quiet jet engine for a period of 1-2 minutes.

INSIVUMEH reported that, during 18-24 June, 7-23 explosions occurred per day at Fuego, generating weak-to-moderate ash plumes to 3,900-4,400 m (12,800-14,400 ft) a.s.l. and drifting with prevailing winds. The explosions during 17-18, 22, and 24 June were accompanied by rumbling sounds, some resembling jet engines that persisted for 1-5 minutes. Small avalanches occurred within the crater and local drainages due to explosion shockwaves on 19 June.

INSIVUMEH reported that explosive activity from Fuego continued in mid-June. Explosions during 12-14 June sent ash plumes as high as 4,600 m (15,000 ft) a.s.l. that drifted 9-11 km S and W. Small avalanches also continued.

INSIVUMEH reported that during 31 May-1 June explosions at Fuego produced ash plumes that rose 350-550 m above the crater and drifted 8 km WNW. During the afternoon and evening of 1 June lahars descended the Las Lajas (SE) and Honda (E) drainages, as well as the Seca (W) drainage which disrupted traffic. Other sections of roadway to the W and S were also affected. Heavy rain continued on 2 June; lahars descended the Las Lajas and El Jute (SE) drainages, carrying blocks as large as 1.5 m in diameter. Explosions during 2-3 June generated ash plumes that rose 550-650 m and drifted 8 km S and SW. Incandescence rose above the crater and avalanches descended the Taniluyá (SW), Trinidad (S), and Ceniza (SSW) drainages.

INSIVUMEH noted in a special report from 25 April that explosions at Fuego were occurring at a rate of 5-6 per hour, generating ash plumes that rose 350-650 m above the crater and drifting 10 km S and SW. Ashfall was reported in Panimaché, Morelia, and Santa Sofía; shock waves vibrated houses in those three towns among others. Avalanches of incandescent blocks reached vegetated areas. Explosions during 26-28 April produced ash plumes that rose 350-800 m and drifted 10 km W. Villagers in Panimaché, Morelia, and Santa Sofía again reported vibrating houses and ashfall. Block avalanches originated from the crater and descended the flanks. During 28-29 April explosions were detected at a rate of 6-8 per hour. Ash plumes rose 750 m and drifted 10 km W and NW. Explosions caused houses on the SW flank to vibrate.

INSIVUMEH reported that during 9-10 April seismic activity at Fuego increased, along with the number and magnitude of explosions. Ash plumes rose 850 m above the crater and drifted 10 km W and SW. Explosions were heard in areas up to 15 km away and shock waves were detected 8 km away. At night incandescent blocks in the Santa Teresa (S), Ceniza (SSW), and Trinidad (S) drainages were noted. During 10-11 April explosions produced ash plumes that rose 500-800 m and drifted 8-10 km W and SW, and caused structures to vibrate in local towns. In a special report from 11 April INSIVUMEH noted that activity had increased. Ash plumes rose as high as 1.1 km and drifted 12 km W. Ashfall was reported in areas downwind, including Panimaché (8 km SW) and Sangre de Cristo (8 km WSW). Avalanches descended the Trinity drainage. Activity continued during 13-14 April though cloud cover prevented visual observations; explosions generated shock waves, and sounds resembling avalanches on the S and SW flanks were reported. During 14-15 April explosions produced ash plumes that rose 760 m and drifted 10 km W and SW. Shock waves were detected in areas within 10 km and explosions were heard within 15 km. At night incandescent blocks in the Santa Teresa (S), Ceniza (SSW), and Trinidad (S) drainages were again noted.

INSIVUMEH reported that during 16-18 January explosions at Fuego produced ash plumes that rose 450-550 m above the crater. A lava flow in the Trinidad (S) drainage was 400 m long and generated avalanches. Other avalanches from the crater descended the Taniluya (SW), Ceniza (SSW), Trinidad, Las Lajas (SE), and Honda (E) drainages. Explosions during 19-20 January produced ash plumes that rose 500-800 m and drifted 10 km SE. Incandescent material was ejected 100-150 high and avalanches continued to descend multiple drainages.

In a special report INSIVUMEH noted that activity at Fuego had increased on 15 December. Lava flows were 500 m long in the Ceniza drainage (SSW), and their emission rate rate had increased. Blocks from lava-flow fronts reached vegetated areas. Six to eight explosions per hour produced ash plumes that rose 550 m and drifted 8 km. The explosions generated shock waves and rattled buildings in nearby villages. The next day lava flows were 600 m long in the Ceniza drainage. Explosions generated ash plumes that rose 450 m and drifted W and SW.

On 21 November INSIVUMEH reported that a recent Strombolian phase at Fuego decreased in intensity. Explosions generated ash plumes that rose 450 m and drifted W and SW. Ashfall was reported in Sangre de Cristo (8 km WSW). During 21-22 November explosions produced ash plumes that rose 450 m and drifted 7 km WNW, as well as loud rumbling sounds heard within 15 km. Lava flows were 300 m long in the Ceniza drainage (SSW). During 25-26 November ash plume from explosions rose 550 m and drifted 10 km W and SW.

INSIVUMEH reported that on 4 November, there was an increase in moderate and strong explosions generating plumes of ash up to 4,500 m a.s.l. The plume extended 10 km and drifted S and SW. Rumbling sounds were strong enough to shake zinc roofs and windows in the towns of Panimaché, Morelia, and Panimaché II. Weak degassing sounds were continuous and resembled the sound of a locomotive train. Pulses of incandescent ejections reached 125-200 m above the summit and caused weak-to-moderate avalanches within the crater. A lava flow that moved into the Trinidad drainage extended 100 m and also generated avalanches. Within the Ceniza drainage, incandescent avalanches traveled ~500 m. CONRED reiterated that the Alert Level remained at Yellow.

INSIVUMEH reported that during 10-11 September explosions from Fuego generated ash plumes that drifted W and NW. Ejected material formed avalanches within the crater. On 10 September lahars that descended the Taniluya (SW) drainage were 15-20 m wide, 1-2 m deep, and carried tree trunks. The lahars blocked roads in Panimache I and II (8 km SW), Morelia (9 km SW), and Santa Sofía (12 km SW) for two hours. The next day lahars descended the Las Lajas and El Jute drainages (SE); they were 30 m wide, 4 m deep, and carried 2-m-diameter blocks, branches, and tree trunks.

Explosions during 11-12 September produced rumbling sounds and ash plumes that rose 500 m. Incandescent material was ejected 100 m and formed avalanches on the crater rim. A 150-m-long lava flow was active in Ceniza (SSW) drainage. During 12-13 September ash plumes from explosions rose 200-400 m and drifted W and NE. Avalanches from ejected material again formed around the crater. Explosions during 14-15 September generated ash plumes that rose 850 m and drifted 10-12 km W and SW. The explosions produced shock waves that rattled structures in villages within10 km of Fuego. Block avalanches descended Ceniza drainage. During 15-16 September explosions generated ash plumes that rose 550 m and drifted SW, and ejected incandescent material 75-100 m high. Ash fell at the observatory.

On 6 September the number and magnitude of explosions increased; rumbling and shock waves were reported 12 km away. Ash plumes rose 750 m and drifted 10 km W and SW. During 7-10 September explosions generated ash plumes that rose 250-400 m; plumes drifted 7 km W and NW on 7 September. Incandescent material was ejected 100 m high and then formed small avalanches. On 9 September heavy rain was followed by lahars in the Las Lajas and El Jute drainages which carried blocks 2 m in diameter. During 9-10 September ash plumes drifted 6 km E and SE.

INSIVUMEH reported that during 28-31 August explosions from Fuego generated ash plumes that rose 450-550 m and drifted 8-10 km W and NW. During 28-29 August incandescent material was ejected 150 m high, and white plumes rose 350 m and drifted NW. During 30-31 August rumbling was heard 15 km away. Lava flows 200 m long were active in the Trinidad drainage on the S flank and produced avalanches. In a special bulletin on 2 September, INSIVUMEH reported that a series of pyroclastic flows descended the Ceniza (SSW) drainage, reaching the base of the volcano. Ash plumes rose 3 km and drifted E, S, W, and NW. During the night lava from the crater flowed 300-400 m down the Ceniza drainage. Explosions were heard, but cloud cover prevented observations through the morning of 3 September.

INSIVUMEH reported that during 22 and 24-25 August explosions from Fuego generated ash plumes that rose 300-500 m and drifted W and NW. Degassing and rumbling sounds were also reported. Active lava flows were 300 and 500 m long in the Taniluyá (SW) and Ceniza (SSW) drainages, respectively. On 23 August lava extrusion increased. Ash plumes rose about 1 km and drifted 12 km W. Fourteen explosions during 26-27 August produced ash plumes that rose 200-500 m and drifted 8 km. Incandescent material was ejected 150 m high, and avalanches from the crater descended the flanks.

INSIVUMEH reported that explosions from Fuego during 13-14 August generated ash plumes that drifted 10 km W and SW. Three lava flows were active; one of the flows traveled SW. Five explosions during 14-15 August ejected incandescent material 100 m high, and generated ash plumes that rose 300 m and drifted 6 km. Lava flows were 150 and 300 m long in the Taniluya (SW) and Ceniza (SSW) drainages, respectively. The next day explosions produced ash plumes that rose 550 m and drifted 10 km W. On 17 August 30-m-wide lahars carrying blocks traveled down the Las Lajas, Ceniza, and El Jute (SE) drainages. During 17-18 August explosions that were heard generated ash plumes that rose 200-300 m and drifted 7 km W. Lava flows in the Taniluya and Ceniza drainages were each 400 m long.

During 18-19 August the flow rate increased; the lava flows were 600 and 800 m long in the Taniluya and Ceniza drainages, respectively. Incandescent blocks from the lava-flow fronts rolled down the flanks and reached vegetated areas. Explosions during 19-20 August ejected incandescent material as high as 150 m, and generated ash plumes that rose 400 m.

On 28 June Vulcanian explosions produced shockwaves felt by local populations within 15 km. Explosions also generated ash plumes that rose 100-200 m and drifted W, and ejected incandescent tephra 150 m above the crater. Ashfall was reported in Panimaché, Morelia, and Sangre de Cristo. A lava flow was active on the flank. During 29 June-2 July explosions generated ash plumes that rose 500-600 m and mostly drifted W and NW.

INSIVUMEH reported that rumbling and sounds resembling jet engines were heard from Fuego during 28-30 May; cloud cover often inhibited visual observations of the crater. On 29 May a lahar carrying blocks up to 50 cm in diameter traveled SE down the Las Lajas and El Jute drainages. On 30 May a plume was observed rising 200 m above the crater and drifting S. During 1-2 and 4 June explosions generated ash plumes that rose at most 800 m and drifted 5-8 km W and NW. Incandescent material was ejected 100 m above the crater and generated avalanches. On 2 June heavy rain caused lahars that traveled down the Ceniza drainage, carrying trees, logs, and blocks. On 3 June diffuse white plumes rose 200 m.

INSIVUMEH reported that during 23-26 April explosions from Fuego generated ash plumes that rose 250-600 m above the crater and drifted at most 10 km W, SW, S, and SE. Incandescent material was ejected 100-200 m above the crater. In a special bulletin on 25 April INSIVUMEH noted that the energy of the explosions had increased, producing rumblings and shock waves that vibrated structures in Panimaché, Morelia, and Sangre de Cristo, as far as 10 km S and SW. A 300-m-long lava flow was active on the S flank in the Trinidad drainage. On 26 April a lava flow in the Taniluya drainage (SW) traveled as far as 400 m. On 28 April activity again increased and 700-m-long lava flows were active in the Taniluya and Ceniza drainages. Incandescent block avalanches reached vegetated areas. Cloud cover prevented observations of the crater. On 29 April explosions generated ash plumes that rose 550 m above the crater and drifted 10 km SSW. Lava flows remained active.

In a special notice on 20 March, INSIVUMEH reported that lava fountains rising 300-400 m above Fuego's crater during the night had decreased along with seismicity and rumbling noises. A lava flow was 1.5 km long in the Ceniza drainage (SSW), and ash plumes drifted SE and S. Explosions during 20-21 and 25-26 March generated ash plumes that rose 0.6-1.2 km and drifted SE, S, and W. Incandescent material was ejected from the crater. Lava flows remained active in the Ceniza drainage and traveled 600 m SW down the Taniluya drainage. Explosions produced ash plumes that rose 400-800 m above the crater and drifted E and W during 21-22 March, rose 300-500 m and drifted 5 km W and NW during 23-24 March, and rose 450 m and drifted W and NW during 24-26 March, which caused ashfall in Panimache I and II (8 km SW), Morelia (9 km SW), and Hagia Sophia.

INSIVUMEH reported that during 13-18 March explosions from Fuego produced ash plumes that rose as high as 4.5 km above the crater, and drifted SW, W, NW, and NE, as far as 12 km. Explosions sometimes ejected incandescent material, generated rumbling noises, and produced shock waves. During 13-14 March ash fell in Panimache I and II (8 km SW) and shock waves vibrated structures. Ash again fell in the Panimache villages as well as in Morelia (9 km SW) during 14-15 March. Avalanches traveled SSW down the Ceniza drainage during 16-19 March.

INSIVUMEH reported that during 6-8 March rumbling noises from Fuego were reported and incandescent material was ejected 50-100 m above the crater. Avalanches traveled SSW down the Ceniza drainage during 6-7 March. Explosions during 8-11 March produced ash plumes that rose up to 450 m above the crater and drifted W, SW, S, SE, and E. During 11-12 March ash plumes drifted 10 km and produced ashfall in the Panimache villages (8 km SW) and Morelia (9 km SW). Lava flows were also observed.

INSIVUMEH reported that during 28 February-1 March explosions from Fuego produced ash plumes that rose less than 250 m and lava flows traveled 300 m S down the Trinidad drainage. Activity increased on 3 March characterized by Strombolian explosions, and lava flows that traveled 1.3 km down the Trinidad drainage and 200 m SW down the Taniluya drainage. Ash plumes rose almost 350 m above the crater and drifted 10 km S. The eruption ended the next day, after 52 hours of activity. White and blue fumarolic plumes rose from the crater. During 4-5 March incandescence 100 m above the crater was observed, and ash plumes rose 200 m and drifted E. Avalanches descended the Taniluya drainage.

INSIVUMEH reported that during 3-8 January explosions from Fuego produced ash plumes that rose less than 350 m and drifted W and SW. Lava flows traveled 300-900 m SW down the Taniluya drainage. During 7-8 January explosions produced plumes that drifted 5 km SW. Incandescence emanated 100 m above the crater.

INSIVUMEH reported that during 8-9 and 11-12 November explosions from Fuego ejected incandescent material 100-200 m above the lava dome, and produced ash plumes that rose 200-430 m and drifted W and SW. Avalanches were generated near the crater. During 8-9 and 11-13 November lava flows traveled 200-500 m SSW down the Ceniza drainage, producing incandescent block avalanches that reached vegetated areas.

Later that day seismicity decreased, ash plumes rose 300 m above the crater and drifted W and NW, fewer pyroclastic flows were observed, and the rate of explosions slowed. Ashfall was reported in Panimaché, Morelia, and Sangre de Cristo. Lava flows in the Ceniza drainage were 1 km long and 150 m wide, and in Las Lajas were 700 m long and 100 m wide. CONRED noted that residents began to return to their homes on 14 September.

During 14-18 September explosions generated rumbling noises; ash plumes that rose 400-900 m above the crater drifted 7-8 km W and SW, causing ashfall in Sangre de Cristo, Panimaché I, and Panimaché II. Lava flows were at most 1.2 km long in the Taniluyá drainage and 200 m long in the Ceniza drainage during 14-16 September; flows were not observed during 17-18 September.

In a special bulletin on 4 September at 1700, INSIVUMEH reported that the eruption from Fuego that began 32 hours earlier had ended. During 6-11 September fumarolic plumes rose 100-150 m above the crater and drifted W and NW. Weak explosions generated ash plumes that rose 300-400 m above the crater and drifted W and NW. During 8-9 September incandescent tephra was ejected to a height of 100 m and caused avalanches in the Taniluyá and the Ceniza (SSW) drainages. A 10-20-m-wide lahar traveled SE down the Las Lajas drainage on 9 September, carrying tree trunks and blocks 1.5 m in diameter. During 10-11 September a lava flow traveled 100 m down the Taniluyá drainage.

In a special bulletin on 3 August, INSIVUMEH reported a new phase of activity at Fuego, characterized by increased seismicity and degassing sounds. Incandescent tephra was ejected 200 m high and a lava flow traveled 500 m down the SW flank into the Taniluya drainage. Pyroclastic flows likely descended the SE and SW flanks. During 4-7 August explosions produced ash plumes that rose 200-400 m above the crater and drifted NW and W. Lava flows traveled 250-300 m down the Taniluyá drainage. Detached blocks from the lava-flow front traveled down the flanks to the vegetated area. Blocks also traveled down the Ceniza drainage (SSW). At night during 5-6 August explosions ejected incandescent tephra 100 m above the crater.

INSIVUMEH reported that on 10 July lahars traveled SE down Fuego's Las Lajas and El Jute drainages carrying blocks 1-1.5 m in diameter. The lahar in Las Lajas was hot and had a sulfur odor. During 10-12 July explosions from Fuego produced ash plumes that rose 150-800 m above the crater and drifted W. On 11 July ashfall was reported in Sangre de Cristo (8 km WSW) and surrounding areas. Tephra avalanches descended the Ceniza (SSW) drainage. During 16-17 July explosions generated ash plumes that rose 200-600 m above the crater and drifted 10 km S and SW. Incandescence emanated from the crater and avalanches descended the Taniluyá (SW) and Ceniza (SSW) drainages.

In a special bulletin on 17 July, INSIVUMEH reported that seismic patterns indicated the beginning of a new phase of activity; avalanches on the S and SW flanks were constantly active, and a new lava flow emerged on the SW flank that traveled 200 m and produced blocks that rolled SW down the Taniluya drainage.

INSIVUMEH reported that during 4-6 July explosions from Fuego produced ash plumes that rose 400-800 m above the crater and drifted W. Rumbling sounds were reported and tephra avalanches descended the S flank. During 7-8 July rumbling and degassing sounds were reported. Although cloud cover mostly prevented observations, a weak plume was noted rising 200-300 m above the crater and drifting NE. Ash fell in Yepocapa (8 km WNW), and on the La Conchita and Monteclaro ranches. Small tephra avalanchas descended the Taniluyá (SW) and Ceniza (SSW) drainages. During 8-9 July a series of seven explosions produced ash plumes that rose 300-900 m above the crater and drifted 10 km W, again causing ashfall in Yepocapa, La Conchita, Monte llano, and Sangre de Cristo (8 km WSW). Explosions on 10 July produced ash plumes that rose 300-600 m above the crater and drifted W. Incandescence rose above the crater during 8-10 July.

INSIVUMEH reported that during 28-29 June activity at Fuego increased; explosions produced ash plumes that rose 500-600 m above the crater and drifted SW. Pulses of incandescence rose 200 m and tephra avalanches descended the Ceniza drainage (SSW). According to Coordinadora Nacional para la Reducción de Desastres (CONRED) on 1 July, seismicity increased and rumbling sounds were audible in areas up to 10 km away. A lava flow 700 m long was active in the Taniluya drainage on the SW flank. In a 2 July report, INSIVUMEH noted that the lava flow on the SW flank was 1,700 m long. Ash plumes rose 500 m above the crater and drifted 10 km W. The seismic network recorded continuous tremor. During 2-3 July explosions produced ash plumes that rose 400 m above the crater and drifted W. A lava flow traveled 400 m down the Taniluya drainage, and blocks from the flows reached vegetated areas.

INSIVUMEH reported that during 21-22 June weather conditions often prevented views of Fuego, however incandescence was observed emanating 150 m above the crater and an explosion produced an ash plume that rose 400 m. A lava flow traveled 1.3 km SSW down the Ceniza drainage and started a fire in a wooded area. Almost constant degassing on 21 June was heard at the Observatorio del Volcán de Fuego (OVFGO) and detected by the seismic network. During 24-26 June explosions generated ash plumes that rose 200-500 m above the crater. Incandescence from the crater was observed and block avalanches descended the flanks.

INSIVUMEH reported that on 6 June lahars descended Fuego's El Jute (SE), Las Lajas (SE), Ceniza (SSW), Santa Teresa (S), and Taniluyá (SW) drainages, and destroyed roads in Yepocapa (8 km WNW). During 6-7 June explosions produced ash plumes that rose 200-500 m above the crater and drifted N, and 12 km S and SW. Lava flows on the SE flank were about 800-900 m long in the Las Lajas drainage, 600 m long in the El Jute drainage, and 250 m long on the SW flank, and produced blocks that rolled and reached vegetated areas. The explosions were accompanied by rumbling sounds and shock waves that were detected in areas 10 km away, including Panimaché and Morelia (~8 km SW).

INSIVUMEH reported that on 1 June hot lahars traveled SE down Fuego's Las Lajas and El Jute drainages carrying blocks 2 m in diameter. During 3-5 June explosions produced ash plumes that rose 500-1,000 m above the crater and drifted W and S. Pulses of incandescence from the crater was observed as well as avalanches on the W flank. Lava flows traveled 700 m down Taniluyá Canyon drainage and 1 km down Las Lajas. During 4-5 June seismicity increased and the lava flow in Las Lajas reached 1.2 km long. Explosions produced ash plumes that rose 600-800 m above the crater and drifted 7 km SW. Shock waves were detected up to 7 km away.

INSIVUMEH reported that during 22-23 May explosions from Fuego produced ash plumes that rose 700 m above the crater and drifted W and SW. Explosions produced shock waves and rumbling noises, and avalanches descended the SW flank towards the Ceniza drainage. Seismic data suggested that on 25 May lava was emitted in the crater, although lava flows were not observed the previous few days. Plumes rose 2 km above the crater and drifted SE, SW, and W. Ashfall was reported in Sangre de Cristo (8 km WSW), Yepocapa (8 km WNW), and in the department of Chimaltenango (21 km NNE). A pyroclastic flow traveled SW down the Las Lajas drainage. During 26-29 May explosions produced ash plumes that rose as high as 1 km above the crater and drifted N, NE, S, and SE. A lava flow traveled 200 m SW and avalanches from the lava-flow front traveled 300 m during 26-27 May. Pulses of incandescence 100 m high were observed during 28-29 May.

On 19 May seismicity at Fuego increased and explosions were heard at 5-10 minute intervals. A 600-m-long lava flow descended the W flank, and a 1-km-long and 20-m-wide lava flow descended the E flank, reaching the base of the volcano. Explosions ejected incandescent tephra 400 m above the crater, and produced ash plumes that rose 5 km above the crater and drifted 30 km S and SW. Coordinadora Nacional para la Reducción de Desastres (CONRED) raised the Alert Level to Orange (the second highest level on a 4-color scale). Pyroclastic flows also descended the flanks, prompting authorities to restrict passage on part of a highway. Ash plumes from the pyroclastic flows rose 3 km above the crater. Ashfall was reported in Morelia (7 km SW), Panimaché I and II (9 km SW), Sangre de Cristo (8 km WSW), and Yepocapa (8 km WNW). Thirteen people from El Porvenir in Alotenango (8 km ENE) evacuated to local shelters. Visual observations and seismicity indicated that activity decreased later that day.

On 20 May a few explosions generated ash plumes that rose 500 m above the crater and drifted 8 km SW. The next day cloud cover prevented observations; however explosions, rumbling, and degassing sounds were reported. On 22 May explosions generated ash plumes that rose as high as 1 km and drifted 10 km S and SE. Rumbling was heard and shock waves were detected. The lava flows were inactive and only incandescence from block avalanches was observed.

INSIVUMEH reported that during 9-10 April explosions from Fuego produced ash plumes that rose 100-900 m above the crater and drifted 10-15 km E and SE. Explosions produced shock waves detected within 8 km of the volcano. Avalanches descended the flanks.

INSIVUMEH reported that during 31 March-1 April and 3-4 April explosions from Fuego produced ash plumes that rose 500-800 m above the crater and drifted 10 km W and NW. During the night lava fountains rose 100-150 m above the crater and formed avalanches that traveled towards the Río Cenizas drainage. Based on analysis of satellite imagery, the Washington VAAC reported that on 1 April an ash plume drifted 13 km WSW and a well-defined thermal anomaly was observed.

INSIVUMEH reported that during 1-2 March explosions from Fuego produced ash plumes that rose 600 m above the crater and drifted 15 km W and SW. Ashfall was reported in Yepocapa (W), Sangre de Cristo (W), and Panimache II (SW). Some explosions produced rumbling and degassing sounds. A 300-m-long lava flow descended the SW flank and produced block avalanches that reached vegetated areas. On 4 March the number of explosions increased to about 4-5 per hour. Explosions generated ash plumes that rose 600 m above the crater and drifted 12 km SSW. Rumbling sounds were heard 7 km away.

INSIVUMEH reported that during 1-3 and on 6 February explosions from Fuego generated ash plumes that rose 400-900 m above the crater; the plumes drifted about 12 km S and SW on 1 February and to the SSW during 2-3 February. On 1 February rumbling noises were heard, incandescence material rose as high as 100 m above the crater, and block avalanches descended the S flank. A new 200-m-long lava flow descended the SW flank into the Taniluya drainage and block avalanches reached vegetation during 2-3 February. On 6 February the lava flow descended towards the Ceniza drainage and block avalanches again reached vegetation. Strong winds caused re-suspended ash to rise 1 km high and drift several kilometers W and S during 1-3 February.

INSIVUMEH reported that during 18-19 and 23-24 January explosions from Fuego generated ash plumes that rose 200-700 m above the crater; the plumes drifted 8-15 km S, SW, and W. During 18-19 January incandescent material rose as high as 100 m above the crater and at night on 23 January incandescent explosions were observed. Block avalanches descended the S flanks.

INSIVUMEH reported that during 11-13 and on 16 January explosions from Fuego generated ash plumes that rose 400-1,000 m above the crater; the plumes drifted 10-15 km in multiple directions. Explosions generated shock waves and rumbling sounds that were detected to the SW, and windows and roofs vibrated in nearby villages. Avalanches traveled SW into the Ceniza drainage and on the W, S, and SW flanks. At night on 13 and 16 January incandescence emanated from the crater.

INSIVUMEH reported that on 6 and 10 January weak explosions from Fuego generated ash plumes that rose 300-600 m above the crater and drifted 10 km WNW and 15 km SW, respectively. Rumbling noises were detected several kilometers away. Incandescence emanated from the crater at night and avalanches descended the S, SW, and SE flanks. Based on information from satellite observations and INSIVUMEH, the Washington VAAC reported that an ash plume drifted SE and later dispersed on 3 January.

INSIVUMEH reported that during 29 December-3 January explosions from Fuego generated ash plumes that rose 400-800 m above the crater; the plumes usually drifted SSW and WSW, but on 30 December they drifted 10 km E and NW. During the week explosions generated shock waves and rumbling sounds that were detected 10 km away. House windows and roofs vibrated in nearby villages. Incandescence emanated from the crater at night, and avalanches traveled SW into the Taniluyá and Ceniza drainages, and S in the Santa Teresa drainage during 29 December-2 January. On 3 January the wind lifted ash to an altitude of 500 m. Based on information from satellite observations, the Washington VAAC reported that a possible ash plume drifted SE on 3 January. That same day, information from INSIVUMEH and satellite imagery indicated small emissions that rose to an altitude of 4.9 km (16,000 ft) a.s.l and drifted SE.

INSIVUMEH reported that during 21-27 December explosions from Fuego generated ash plumes that rose 200-800 m above the crater; the plumes drifted 10-12 km W, NW, SW, and S during 21-23 and 26-27 December. During 21-23 and 26-27 December explosions generated shock waves and rumbling sounds that were detected 12 km away. House windows and roofs vibrated in nearby villages on 27 December. Incandescence emanated from the crater at night, and avalanches traveled SW into the Taniluyá and Ceniza drainages, and S in the Santa Teresa drainage. Based on satellite observations, the Washington VAAC reported that a gas plume with possible ash drifted 9 km S on 24 December.

INSIVUMEH reported that on 9 and 13 December explosions from Fuego produced rumbling sounds and ash plumes that rose 300-600 m above the crater and drifted W, SW, and S. Block avalanches descended the SW flank toward the Ceniza drainage.

INSIVUMEH reported that on 1 December explosions from Fuego produced ash plumes that rose 800 m above the crater and drifted to the S. Avalanches descended toward Ash Creek. During 5-6 December ash plumes rose to an altitudes of 400-500 m above the crater and drifted to the W. A 150-m-long lava flow descended toward Ash Creek and avalanches reached vegetated areas.

Based on information from INSIVUMEH, the Washington VAAC reported gas and ash emissions on 2 December and a possible ash plume rose to an altitude of km (10,000 ft) a.s.l. on 6 December.

INSIVUMEH reported that during 20-21 October explosions from Fuego produced shock waves that were detected nearby, rumbling sounds, and ash plumes that rose 500 m above the crater and drifted W. Incandescence emanated from the crater at night, and avalanches traveled SW into the Taniluyá, Ceniza, and Trinidad drainages. On 23 October, the Washington VAAC reported that an ash plume was observed in satellite imagery.

INSIVUMEH reported that during 14-15 October explosions from Fuego produced shock waves that were detected nearby, rumbling sounds, and ash plumes that rose 700 m above the crater and drifted S. A small avalanche traveled S in the Santa Teresa drainage. Cloud cover prevented visual observations during 16-18 October; however, explosions and block avalanches were heard.

INSIVUMEH reported that during 13-14 September explosions from Fuego produced ash plumes that rose 800 m above the crater. The explosions occasionally produced shock waves detected 7 km away. Incandescence at night emanated from the crater and from avalanches on the flanks. During 15-16 September cloud cover prevented observations of the crater but explosions were heard. Block avalanches descended the flanks and an ash plume drifted 7 km W. During 19-20 September explosions produced ash plumes that rose 500 m above the crater and drifted W.

INSIVUMEH reported that during 13-14 July explosions from Fuego produced ash plumes that rose 700 m above the crater and drifted W. Incandescence at night emanated from a 100-m-long lava flow on the S flank. Block avalanches reached vegetated areas.

INSIVUMEH reported that during 23-24 June explosions from Fuego produced ash plumes that rose 150-200 m above the crater and drifted W. Incandescent bursts rose 100 m above the crater. During 23-24 and 27-28 June lava flows traveled 200 m down the Ceniza drainage to the SW and detached blocks reached vegetated areas.

INSIVUMEH reported that during 30-31 March and 4-5 April explosions from Fuego produced ash plumes that rose 200-700 m above the crater and drifted W, SW, and S. Lava flows traveled almost 200 m SW down the Ceniza drainage and produced block avalanches from lava-flow fronts. Crater incandescence was observed at night.

INSIVUMEH reported that during 17-18 and 20-22 March explosions from Fuego produced ash plumes that rose 300-600 m above the crater and drifted 5-8 km W, SW, and S. Incandescent material was ejected as high as 100 m above the crater. Avalanches traveled SW, into the Taniluyá, Santa Teresa, Ceniza, and Trinidad drainages.

INSIVUMEH reported that during 24-25 and 27-28 February explosions from Fuego produced ash plumes that rose 500-700 m above the crater and drifted W and SW. Incandescent material was ejected as high as 100 m above the crater. Avalanches traveled SW, descending the Taniluyá, Ceniza, and Trinidad drainages.

INSIVUMEH reported that during 16-17 and 20-22 February explosions from Fuego produced ash plumes that rose 300-800 m above the crater. Some plumes drifted E. Incandescent material was ejected as high as 100 m above the crater. Avalanches traveled E as well as SW, descending the Taniluyá, Santa Teresa, Ceniza, and Trinidad drainages.

INSIVUMEH reported that during 9-10 and 13-14 February explosions from Fuego produced ash plumes that rose 300-800 m above the crater and drifted W, NW, N, and NE. The explosions generated shock waves that rattled structures in Panimaché and Sangre de Cristo. Crater incandescence was observed at night and avalanches descended the flanks. Fine ashfall was reported in communities downwind during 9-10 February, including Panimaché I and II (8 km SW), Morelia (9 km SW), and Sangre de Cristo (8 km WSW).

INSIVUMEH reported that during 2-3 February Fuego produced 27 explosions with ash plumes that rose 300-500 m above the crater and drifted 7 km W and SW. The explosions generated shock waves detected as far away as 5 km W and SW, in Sangre de Cristo, Panimache I and II, and Morelia. Block avalanches descended the Santa Teresa, Taniluyá, Cenizas, and Trinidad drainages to the SW. During 6-8 February explosions produced ash plumes that rose 500 m above the crater and drifted W and SW. At night incandescence was observed emanating from the crater and explosions sometimes ejected incandescent material 100 m above the crater rim.

INSIVUMEH reported that during 19-20 and 23-24 January explosions from Fuego produced ash plumes that rose 500-800 m above the crater and drifted W, NW, and S. Incandescent material was ejected as high as 100 m above the crater. Rumbling and degassing sounds were noted, and avalanches descended a few drainages.

On 10 January, INSIVUMEH reported an increase in the number and magnitude of explosions from Fuego since mid-December. During the previous three days explosions had produced ash plumes that rose 1 km above the crater and drifted 25 km mainly S and SW, and remained in the atmosphere for several hours. INSIVUMEH recommended that civil aviation authorities restrict flying within 25 km S and SW of Fuego. During 13-14 and 16-18 January explosions produced ash plumes that rose 200-500 m above the crater and drifted SW, E, and NE. Rumbling was heard and shock waves were detected. At night during 13-14 January, explosions ejected incandescent material as high as 75 m above the crater.

INSIVUMEH reported that during 5-6 January explosions from Fuego produced ash plumes that rose 500-800 m above the crater and drifted 10 km S and SW. The explosions caused windows and roofs to rattle in areas 6 km away. Fine ashfall was reported in communities downwind including Panimaché (6 km SW), Morelia (7 km SW), and Yepocapa (8 km WNW). Incandescence from the crater was observed at night. On 8 January, the Washington VAAC reported multiple gas-and-ash plumes that rose to an altitude of 5.2 km (17,000 ft) a.s.l. were observed in satellite imagery. During 10-11 January INSIVUMEH again reported that explosions produced ash plumes that rose 500-800 m above the crater and shock waves that were detected as far away as 7 km. Plumes drifted 15 km W and block avalanches descended a few drainages.

INSIVUMEH reported that during 29-30 December explosions from Fuego, almost constant at times, produced dense ash plumes that rose 600-800 m above the crater and drifted 8 km W and SW. Avalanches occurred on the flanks. The Washington VAAC reported that several small emissions observed in satellite imagery drifted W on 1 January. INSIVUMEH noted that during 3-4 January explosions generated ash plumes that rose 800-1,000 m above the crater and fanned out towards the S and SW. The plumes drifted almost 15 km and caused ashfall in areas downwind, including Panimaché (6 km SW), Morelia (7 km SW), and Santa Sofia (12 km SW). Incandescence from the crater was observed at night.

On 22 December, the Washington VAAC reported that an ash plume from Fuego observed in satellite imagery drifted 28 km NW. INSIVUMEH reported that on 23 December explosions produced ash plumes that rose 600-1,200 m above the crater and drifted 10-15 km SE. Explosions the next day generated ash plumes 400 m above the crater. Incandescent material was ejected 100 m above the crater at night during 27-28 December. On 28 December ash plumes from explosions rose as high as 500 m above the crater and drifted more than 5 km S and SW. Avalanches descended multiple drainages.

On 17 December, INSIVUMEH reported that explosions from Fuego produced ash plumes that rose 300-800 m above the crater and drifted E and SE. Later that day the number of explosions increased, occurring at a rate of 12-15 per hour. Ash plumes rose 500-900 m above the crater and drifted E and NE. Ashfall was reported in Antigua Guatemala, 18 km NE, and San Juan Alotenango, 9 km ENE. On 20 December, weak explosions generated ash plumes that rose 500 m above the crater and drifted W and NW, and occasional rumbling noises.

Based on analysis of satellite imagery, the Washington VAAC reported that on 4 December a diffuse plume of gas and possibly ash drifted SW. On 6 December, INSIVUMEH reported that explosions produced ash plumes that rose 900 m above the crater and drifted 6 km SW.

During 18-22 November, INSIVUMEH reported that explosions from Fuego produced ash plumes that rose as high as 1 km above the crater and drifted S, SW, and W. Incandescent material was ejected 100 m above the crater and avalanches occurred. Ashfall was reported in areas downwind, including in villages 10 km W. Some explosions were accompanied by rumbling noises and shock waves detected as far away as 8 km.

On 12 November, INSIVUMEH reported that explosions from Fuego produced ash plumes that rose 800 m above the crater and drifted S and SW. At night, incandescent material was ejected to low heights above the crater. Avalanches occurred around the crater rim. Based on analyses of satellite imagery, the Washington VAAC reported that during 12-13 November ash plumes drifted as far as 37 km SW.

During 28-29 October, INSIVUMEH reported that explosions from Fuego produced ash plumes that rose 300-600 m above the crater. Incandescent material was ejected 75 m above the crater, and rumbling and degassing sounds were occasionally heard. Avalanches descended the W flank. On 18 October, ashfall was reported in Sangre de Cristo, 10 km WSW. Based on analyses of satellite imagery, the Washington VAAC reported that on 31 October an ash cloud was detected up to 20 km W of Fuego.

INSIVUMEH reported that on 2 October a seismic station near Fuego recorded some explosions and a possible lahar that traveled SE. Weather prevented visual observations. During 4-5 October, explosions ejected incandescent material above the crater and produced ash plumes that rose 500-700 m above the crater.

During 12-17 August, INSIVUMEH reported that explosions from Fuego produced ash plumes that rose to altitudes of 4.1-4.7 km (13,500-15,400 ft) a.s.l. and drifted W and NW. Rumbling and "degassing" sounds were associated with the explosions. At night during 15-16 August explosions ejected incandescent material 100 m above the crater. On 17 August blocks descended the S flanks.

INSIVUMEH reported on 19 July that six explosions from Fuego produced ash plumes that rose to an altitude of 4.4 km (14,400 ft) a.s.l. and drifted W and SW. Rumbling and "degassing" sounds were associated with the explosions. Light ashfall was reported in Sangre de Cristo, 10 km WSW. The seismic network had recorded a total of 17 explosions within the previous 24 hours.

INSIVUMEH reported that during 10-11 June multiple explosions from Fuego produced ash plumes that rose to altitudes of 4.1-4.3 km (13,500-14,100 ft) a.s.l. and drifted NW. Rumbling and "degassing" sounds were associated with the explosions. Occasionally incandescent material was ejected as high as 75 m above the crater and avalanches descended the flanks. Fine ashfall was reported in Sangre de Cristo, 10 km WSW. During a period of increased activity on 11 June, shock waves were detected as far away as 5 km.

On 20 May, INSIVUMEH reported that explosions from Fuego produced ash plumes that rose to altitudes of 4.4-4.8 km (14,400-15,700 ft) a.s.l. and drifted SW. Incandescent material was ejected to heights of 100 m and avalanches descended the S and W flanks.

On 26 April, INSIVUMEH reported that explosions from Fuego produced gray plumes that rose to altitudes of 4.3-4.6 km (14,100-15,100 ft) a.s.l. and drifted E. A few of the explosions produced avalanches around the volcano, and rumbling sounds were heard.

On 26 February and 2 March, INSIVUMEH reported that explosions from Fuego produced gray plumes that rose to altitudes of 4.1-4.5 km (13,500-14,800 ft) a.s.l. and drifted E and NE. Avalanches descended the S and W flanks. Weak incandescence emanated from the crater. On 2 March, ash fell in areas downwind.

On 22 January, INSIVUMEH reported that explosions from Fuego produced gray plumes that rose to altitudes of 4.4-4.8 km (14,400-15,700 ft) a.s.l. and drifted 5-12 km SW. Incandescent material was ejected to heights of 75 m and avalanches descended the flanks. Based on analyses of satellite imagery, the Washington VAAC reported that on 25 January a dense ash cloud drifted 15 km NW. The next day an ash cloud drifted 11 km W.

Based on analyses of satellite imagery, the Washington VAAC reported that on 6 January an ash plume from Fuego drifted 45 km SE. On 8, 11, and 12 January, INSIVUMEH reported that explosions produced ash plumes that rose to altitudes of 4-4.7 km (13,000-15,400 ft) a.s.l. Plumes drifted as far as 10 km in multiple directions, causing ashfall in some areas. Incandescent material was ejected to heights up to 75 m. Some explosions were accompanied by rumbling noises and shock waves that rattled structures up to 7 km away. Avalanches descended the flanks.

On 11, 14, and 15 December, INSIVUMEH reported that explosions from Fuego produced ash plumes that rose to altitudes of 4.1-4.7 km (13,500-15,400 ft) a.s.l. and drifted 8-12 km W and SW. Incandescence from the main crater and rumbling noises were noted. Avalanches descended the S and W flanks. Based on analyses of satellite imagery, the Washington VAAC reported that on 12 December a gas-and-ash plume drifted 20 km W. On 15 December, ashfall was reported in areas SW.

Based on analyses of satellite imagery, the Washington VAAC reported that on 29 November a small plume from Fuego, possibly containing ash, drifted 10 km SW. A thermal anomaly was also detected. On 30 November and 1 December, INSIVUMEH reported that explosions produced ash plumes that rose to altitudes of 4.3-4.7 km (14,100-15,400 ft) a.s.l. and drifted 8-15 km W and SW. Rumbling noises were noted and incandescent block avalanches were generated.

Based on analyses of satellite imagery, the Washington VAAC reported that on 12 November a gas plume from Fuego, possibly containing ash, drifted SSW. On 13 November, INSIVUMEH reported that explosions produced ash plumes that rose to altitudes of 4.2-4.7 km (13,800-15,400 ft) a.s.l. and drifted 7 km S. Rumbling noises were noted and incandescence was detected. White fumarolic plumes rose 100 m and drifted S and SW. Small plumes of ash on 16 November were seen on satellite imagery.

Based on analyses of satellite imagery and a pilot observation, the Washington VAAC reported that on 20 October an apparent ash plume from Fuego drifted SSW. On 21 October, multiple ash emissions resulted in an ash cloud that drifted 55 km S. Emissions were also reported the next day. On 26 October, a diffuse gas-and-ash plume drifted W. That same day, INSIVUMEH reported that explosions produced plumes that rose to altitudes of 4.4-4.8 km (14,400-15,700 ft) a.s.l. and drifted 10 km S and SW. Ash fell downwind, rumbling and degassing sounds were reported, and avalanches of blocks descended the flanks. On 27 October, a few ash clouds seen on satellite imagery drifted 90 km NW.

On 9, 12, and 13 October, INSIVUMEH reported that explosions from Fuego produced ash plumes that rose to altitudes of 4.1-4.6 km (13,500-15,100 ft) a.s.l. and drifted W. Some explosions were accompanied by rumbling noises, and avalanches of blocks descended the flanks. On 9 October, a lahar traveled down the Lajas ravine, carrying blocks up to 50 cm in diameter.

On 10 and 14 September, INSIVUMEH reported that explosions from Fuego produced ash plumes that rose to altitudes of 4.1-4.7 km (13,500-15,400 ft) a.s.l. and drifted as far away as 10 km W, SW, and S. Some explosions were accompanied by rumbling noises and shock waves. Incandescent material was ejected 100 m high and avalanches descended multiple ravines.

Based on information from the Tegucigalpa MWO, the Washington VAAC reported that ash was detected within 15 km of Fuego on 19 August. Ash was not identified in satellite imagery. On 21 and 25 August, INSIVUMEH reported that explosions produced plumes that rose to altitudes of 4.2-4.6 km (13,800-15,100 ft) a.s.l. and drifted 5-7 km W and SW. On 21 August rumbling sounds were accompanied by incandescent tephra ejected 75 m high. On 25 August, ashfall was reported in areas to the SW.

On 31 July and 3 August, INSIVUMEH reported that explosions from Fuego produced ash plumes that rose to altitudes of 4-4.6 km (13,100-15,100 ft) a.s.l. and drifted W. Some explosions were accompanied by rumbling noises. Incandescent material was ejected 75 m high and avalanches occurred on the main cone. Fumarolic plumes rose 200 m and drifted W and NW. The frequency of explosions significantly increased during 2-3 August.

INSIVUMEH reported that on 21 May lahars descended the Santa Teresa and Ceniza ravines to the W and SW of Fuego, respectively, and carried fine material as well as blocks up to 2 m in diameter. During 25-26 May, explosions produced ash plumes that rose to altitudes of 4.1-4.7 km (13,500-15,400 ft) a.s.l. and drifted W, SW, S, and SE. Some rumbling noises were reported. On 25 May, fumarolic plumes rose to an altitude of 4.2 km (13,800 ft) a.s.l. and drifted S and SE. Ashfall was reported in areas to the W and WSW on 26 May.

On 27 and 30 March, INSIVUMEH reported that explosions from Fuego produced ash plumes that rose to altitudes of 4.1-4.8 km (13,500-15,700 ft) a.s.l. and drifted S and SW. Some explosions were accompanied by rumbling noises, shock waves detected 10 km away, and avalanches of blocks down the W and SW flanks. Fumarolic plumes drifted NE and SW. On 30 March, incandescent material was ejected 75 m into the air. Based on analysis of satellite imagery, the Washington VAAC reported that on 31 March an ash plume drifted E.

On 12, 16, and 17 March, INSIVUMEH reported that explosions from Fuego produced ash plumes that rose to altitudes of 4.2-4.8 km (13,800-15,700 ft) a.s.l. and drifted S and SW. Incandescent material was ejected 75 m into the air. Some explosions produced rumbling sounds heard in nearby towns. White plumes rose 150-200 m above the summit. During 16-17 March, fine ashfall was reported in areas downwind.

Based on analysis of satellite imagery and SIGMET notices, the Washington VAAC reported that during 12-13 March ash plumes drifted S and SW. On 13 March, the ash plume rose to an altitude of 5 km (16,500 ft) a.s.l.

Based on analysis of satellite imagery, the Washington VAAC reported that on 5 March multiple ash plumes from Fuego drifted W. On 6 and 10 March, INSIVUMEH reported that explosions produced ash plumes that rose to altitudes of 4.2-4.8 km (13,800-15,700 ft) a.s.l. and drifted 12-15 km S and SW. Some strong explosions were accompanied by rumbling noises, shock waves detected 8 km away, avalanches of blocks down all flanks, and ash plumes that rose to an altitude of 5 km (16,400 ft) a.s.l. Ashfall was reported in areas to the SW.

Based on analysis of satellite imagery, the Washington VAAC reported that on 18 February ash plumes from Fuego rose to an altitude of 6.1 km (20,000 ft) a.s.l. and drifted WSW. On 20 and 24 February, INSIVUMEH reported that explosions produced ash plumes that rose to altitudes of 4.1-4.7 km (13,500-15,400 ft) a.s.l. and drifted 6-8 km SW. Some explosions produced rumbling sounds and shock waves. Incandescent material was ejected 150 m above the crater. Incandescent avalanches of blocks traveled down the W and SW flanks.

On 6, 8, and 10 February, INSIVUMEH reported that multiple explosions from Fuego produced ash plumes that rose to altitudes of 4.1-5.4 km (13,500-17,700 ft) a.s.l. and drifted S and SW. Ashfall was reported in areas downwind. Some explosions produced rumbling sounds and constant avalanches of blocks descended the flanks. On 8 February, explosions were accompanied by shock waves that were detected 10-15 km away.

Based on information from the Central American FIR, the Washington VAAC reported that on 14 January an ash plume from Fuego rose to an altitude of 4.9 km (16,000 ft) a.s.l. and drifted WSW. On 19 and 20 January, INSIVUMEH reported that explosions produced ash plumes that rose to altitudes of 4.1-4.6 km (13,500-15,100 ft) a.s.l. and drifted 7 km NW, W, and SW. Some explosions produced rumbling sounds. Avalanches occurred on the S and SW flanks.

INSIVUMEH reported that during 8-9 January, multiple explosions (3-5 per hour) from Fuego produced ash plumes that rose to altitudes of 4.3-5.4 km (14,100-17,700 ft) a.s.l. and drifted 10-15 km S and SW. The explosions produced rumbling sounds and shock waves that were detected 10-15 km away. Ashfall was reported in areas downwind. Constant avalanches of blocks descended the S and SW flanks. Based on analysis of satellite imagery and information from the Tegucigalpa MWO, the Washington VAAC reported that on 10 January a diffuse plume drifted W.

Based on analysis of satellite imagery, the Washington VAAC reported that on 1 January two ash plumes from Fuego drifted N. INSIVUMEH reported that during 4-6 January multiple explosions produced ash plumes that rose to altitudes of 4.1-5.1 km (13,500-16,700 ft) a.s.l. and drifted 12 km W and SW. Ashfall was reported in areas downwind. Some explosions produced rumbling sounds and shock waves that were detected 10 km away. Constant avalanches of blocks descended the S and SW flanks.

Based on NOTAM's ("Notices to Airmen"), the Washington VAAC reported that on 9 December a possible gas-and-ash plume from Fuego rose to an altitude of 4.9 km (16,000 ft) a.s.l., drifted N, and dissipated rapidly. INSIVUMEH reported that on 12 December explosions produced ash plumes that rose to altitudes of 4.1-5 km (13,500-16,400 ft) a.s.l. and drifted SSW. The explosions produced rumbling and degassing sounds, and shock waves were detected 10 km away.

INSIVUMEH reported that during 20-21 and 25 November explosions from Fuego produced ash plumes that rose to altitudes of 4.1-4.6 km (13,500-15,100 ft) a.s.l. and drifted W and S. The explosions produced rumbling and degassing sounds, and shock waves were detected 10 km away. Lava flowed 150 m W towards the Taniluyá ravine and incandescent material rolled down the flanks.

Based on information from the Tegucigalpa MWO, the Washington VAAC reported that on 18 September a possible ash plume from Fuego rose to an altitude of 4.3 km (14,000 ft) a.s.l. and drifted SSW. INSIVUMEH reported on 24 September that a lava flow traveled 300 m W towards the Seca ravine. Avalanches were generated from the lava flow front. Explosions generated ash plumes that rose to an altitude of 4.1 km (13,500 ft) a.s.l. and drifted W.

INSIVUMEH reported that on 20 August lahars descended several rivers to the S and SE of Fuego, carrying fine material as well as blocks up to 1 m in diameter. Strong currents in Río Cenizas and El Jute were noted. During 25-26 August, explosions produced ash plumes that rose to an altitude of 4.1 km (13,500 ft) a.s.l. and drifted SW. Fumarolic plumes rose to an altitude of 4 km (13,100 ft) a.s.l. and also drifted SW. A 300-m-long lava flow traveled W towards the Santa Teresa ravine.

INSIVUMEH reported that a lahar descended El Jute River to the SE of Fuego on 31 July, carrying fine material as well as blocks. A report on 1 August indicated that explosions produced ash plumes that rose to an altitude of 4.1 km (13,500 ft) a.s.l. and drifted W and SW. Rumbling noises and shockwaves occasionally accompanied the explosions.

INSIVUMEH reported that on 4 July there were rumbling noises from Fuego and the seismic network detected multiple explosions. A lava flow traveled 100 m W towards the Santa Teresa ravine. A lahar carrying blocks descended the Ceniza ravine to the SW. On 7 and 8 July, explosions produced ash plumes that rose to altitudes of 4-4.5 km (13,100-14,800 ft) a.s.l. and drifted S, SE, and SW. Incandescence at the summit was observed and constant avalanches of blocks from lava-flow fronts descended the W flank.

On 18 June, INSIVUMEH reported that explosions from Fuego produced ash plumes that rose to an altitude of 4.3 km (14,100 ft) a.s.l. and drifted W and SW. Incandescent material was ejected 50 m above the crater. Constant avalanches of blocks descended the W flank and rumbling and degassing noises were reported. On 20 June, a lahar that was hot in areas, descended the Ceniza drainage to the SW, dragging tree branches and blocks 0.5-1 m in diameter.

The Washington VAAC reported that an ash plume from Fuego was visible on satellite imagery on 23 April and drifted SW. On 28 April, INSIVUMEH reported that explosions (1 per hour) produced ash plumes to an altitude of 4.4 km (14,400 ft) a.s.l. The plumes drifted 5 km SW. The explosions produced noises audible 15 km away and shock waves that rattled windows and structures in nearby villages.

INSIVUMEH reported that explosions (1-2 per hour) from Fuego produced ash plumes to altitudes of 4.3-4.7 km (14,100-15,400 ft) a.s.l. during 15-21 April. The plumes drifted 5-8 km SW and ashfall was reported from areas downwind. The explosions produced rumbling and degassing sounds, and shock waves that rattled windows and structures 5-15 km away. The Washington VAAC reported that multiple ash plumes were visible on satellite imagery during 18-19 April and drifted mainly SW.

INSIVUMEH reported that during 22-25 March more frequent explosions (4-5 per hour) from Fuego produced ash plumes to altitudes of 4.1-4.6 km (13,500-15,100 ft) a.s.l. The plumes drifted 6-8 km S and SE. Most explosions produced degassing and rumbling noises, and shock waves that vibrated windows and ceilings within a 5-8 km radius.

INSIVUMEH reported on 24 January that explosions from Fuego produced ash plumes that rose to altitudes of 4.2-4.5 km (13,800-14,800 ft) a.s.l. ands drifted S, SW, and W. Some explosions produced shock waves that were detected 3 km away. At night, small avalanches of blocks traveled W towards the Taniluyá ravine. Based on reports from INSIVUMEH, CONRED reported on 28 January that the Alert Level was lowered to Green.

Based on observations of satellite imagery, the Washington VAAC reported that a narrow plume of gas and possible ash drifted SW on 30 January.

INSIVUMEH reported on 11 January that weak explosions from Fuego produced ash plumes that rose to altitudes of 4.1-4.3 km (13,500-14,100 ft) a.s.l. CONRED reiterated that the Alert Level remained at Yellow.

Based on observations of satellite imagery, the Washington VAAC reported that ash plumes from Fuego rose to an altitude of 5.2 km (17,000 ft) a.s.l. drifted SW on 21 December. Gas or ash plumes were seen on satellite imagery on 23 December and drifted W. According to CONRED, INSIVUMEH reported on 24 December that an ash plume drifted SW. CONRED reiterated that the Alert Level remained at Yellow.

INSIVUMEH reported on 12 October that explosions from Fuego produced ash plumes that rose to altitudes of 4.2-4.8 km (13,800-15,700 ft) a.s.l. and drifted W and SW. Ashfall was reported from areas to the W. The explosions were accompanied by rumbling noises, degassing sounds, and shock waves detected up to 15 km away. The Washington VAAC reported a thermal anomaly along with ash plumes drifting W and NW that were visible on satellite imagery during 15-16 December. INSIVUMEH reported that on 17 December, Fuego returned to normal levels after the 15-16 December eruption. A few explosions were registered by the seismic network and ash plumes rose to altitudes of 4.5 km (17,800 ft) a.s.l. plumes drifted S and SW.

INSIVUMEH reported on 10 October that explosions from Fuego produced ash plumes that rose to altitudes of 4-5 km (13,000-16,400 ft) a.s.l. and drifted N and NW. Explosions were accompanied by rumbling noises and sounds resembling an aircraft engine. Avalanches due to collapses from the growing cone in the inner crater descended W into the Taniluyá and Santa Teresa ravines.

On 24 August, INSIVUMEH reported that fumarolic plumes from Fuego rose to an altitude of 3.9 km (12,800 ft) a.s.l. and drifted W. A lahar carried tree trunks, branches, and blocks down the Lajas drainage to the SE. A lahar again affected the drainage on 27 August. Explosions on 28 August produced ash plumes that rose to an altitude of 4.1 km (13,500 ft) a.s.l.

INSIVUMEH reported that on 8 August, a Strombolian eruption of Fuego produced gas-and-ash plumes that rose to altitudes of 4.8-5.6 km (15,700-18,400 ft) a.s.l. and drifted W and SW. Lava flows advanced and avalanches of incandescent blocks traveled down river valleys, including the Ceniza river valley to the SW. Several pyroclastic flows descended the flanks and ashfall was reported in villages to the W, SW, and S. CONRED raised the Alert Level to Orange (level 3 on a scale of 1-4) in surrounding communities on 8 August, based on a later report from INSIVUMEH.

On 9 August, there was a substantial decrease in vigor of the Strombolian eruption. Explosions produced plumes to altitudes of 4.4-4.8 km (14,400-15,700 ft) a.s.l. and drifted SW. A lava flow traveled 1.5 km SW down the Ceniza river valley and landslides of incandescent blocks were observed. INSIVUMEH issued a report later that day stating that the activity had further decreased to normal levels. A few explosions produced plumes to an altitude of 4.3 km (14,100 ft) a.s.l. and drifted SW.

On 10 August, CONRED decreased the Alert Level to Yellow. INSIVUMEH reported that the lava flows that were active during 8-9 August were no longer visible. On 10 and 13 August, small explosions produced plumes to an altitude of 4.3 km (14,100 ft) a.s.l. and drifted SW.

INSIVUMEH reported that explosions from Fuego expelled incandescent material 50-75 m above the crater on 1 August. Incandescent avalanches traveled 500-700 m down the S and W flanks. Rumbling noises and shock waves were noted at nearby locations. On 2 August, a moderate eruption produced pyroclastic flows that traveled approximately 2 km SSW down the Ceniza River valley. A resultant ash plume rose to an altitude of 5.3 km (17,400 ft) a.s.l. and produced ashfall in areas to the S, SW, and W for several minutes.

CONRED raised the Alert Level to Yellow in surrounding communities on 22 July, based on a report from INSIVUMEH. INSIVUMEH reported that Vulcanian explosions produced ash plumes to altitudes of 4.1-5.2 km (13,500-17,100 ft) a.s.l. and expelled incandescent material 75-250 m above the crater. The explosions were accompanied by rumbling noises and shock waves that rattled ceilings and windows within a 25 km radius. Ashfall was reported from areas approximately 7-8 km to the SW, and incandescent avalanches of blocks rolled 500-800 m down the S flanks towards areas of vegetation. A new lava flow that initiated from an area 100 m below the S edge of the central crater traveled about 100 m.

INSIVUMEH reported that on 27 June, a new 100-m-long lava flow from Fuego was observed that somewhat paralleled the previous flow from March/April 2007. The older lava flow on the S flank continued to advance and produce incandescent blocks that rolled W into the Taniluyá River valley. On 29 June, pyroclastic explosions propelled material about 75 m above the crater. Seven explosions produced whitish plumes to an altitude of about 4 km (13,100 ft) a.s.l. and drifted S.

According to CONRED, INSIVUMEH reported on 1 July that during a Strombolian eruption, lava was propelled 200-300 m above the summit. Resulting lava flows traveled about 800 and 1,300 m to the W. Rumbling sounds were heard and shockwaves rattled windows in near by villages. Ash plumes rose to an altitude of 3.9 km (12,800 ft) a.s.l. and drifted W. Multiple pyroclastic flows traveled 1.3-2 km to the W. Based on the report, CONRED raised the Alert Level to Orange in surrounding communities.

On 25 May, CONRED reported that the Alert Level for Fuego was lowered from Yellow to Green based on recent communication with nearby communities and monitoring by scientists at INSIVUMEH. During 28-29 May, INSIVUMEH reported that the lava flow on the S flank continued to advance and produce incandescent blocks that rolled W into the Taniluyá River valley. Low rumbling noises were heard during 26-27 May and occasionally accompanied pyroclastic explosions. Additional explosions produced plumes to an altitude of 4.1 km (13,500 ft) a.s.l. and expelled incandescent material about 100 m above the crater. Avalanches of blocks were observed on the S and SW flank. Gray plumes drifted S. Steam-and-gas plumes rose to an altitude of 4.6 km (15,100 ft) a.s.l.

INSIVUMEH reported that on 20 and 23 April, Strombolian activity was observed at Fuego; incandescent material was ejected about 50-75 m above the summit and blocks descended 300 m down the S and W flanks. On 20 April, sounds resembling locomotives accompanied the eruption, and lava overflowed the crater on the S flank and traveled 100 m. The Washington VAAC reported that an intense hotspot seen on satellite imagery on 21 April was likely caused by a lava flow to the SW, according to information from INSIVUMEH. A plume drifting SW was also visible on satellite imagery and may have been a result of fires started by lava flows; the plume may have also contained light ash and gas. On 23 April, INSIVUMEH reported that pyroclastic flows and incandescent avalanches traveled down SE and SW ravines. Ash explosions caused light ashfall in areas S of the volcano and fumarolic and gas plumes rose to an altitude of 4 km (13,000 ft) a.s.l.

Based on satellite imagery, the Washington VAAC reported that a small plume from Fuego drifted E on 21 March. During 21-22, 24, and 26-27 March, INSIVUMEH reported that explosions produced gas-and-ash plumes that rose to altitudes of 4.7-5.1 km (15,400-16,700 ft) a.s.l. Ashfall was reported from areas 5-8 km SSE and 9 km W. On 24 March, explosions were followed by lava blocks rolling down the W flank toward the Taniluyá River valley and gas emissions. Resultant plumes drifted 15 km SW. Similar activity on 26 March caused ashfall in areas 10-25 km away to the W and SE. On 27 March, the Washington VAAC reported that another small plume was visible on satellite imagery drifting W.

INSIVUMEH reported that incandescent material from Fuego was ejected 200 m above the summit on 15 March. The activity was accompanied by rumbling noises and shockwaves that vibrated windows several kilometers away. Two lava flows were observed; one traveled about 1,500 m W toward the Taniluyá River valley. An ash plume drifted S and SW. On 16 March, Strombolian activity propelled material 300 m above the summit and shockwaves were felt as far as 15 km away. The lava flows from 15 March advanced and three more flows were observed in different ravines on 16 March. Ash plumes rose to an altitude of 5.4 km (17,799 ft) a.s.l. and drifted S, SW, and E. Two pyroclastic flows traveled about 800 m; one NW and another W and SW.

Based on pilot reports, INSIVUMEH reports, and satellite imagery, the Washington VAAC reported that ash plumes reached altitudes of 4.1-6.1 km (13,500-20,000 ft) a.s.l. during 15-16 March. A hotspot was visible on satellite imagery both days.

Based on a pilot report and information from INSIVUMEH, the Washington VAAC reported that a diffuse plume from Fuego reached an altitude of 4 km (13,000 ft) a.s.l. and drifted NE. A hotspot over the crater was visible on satellite imagery. INSIVUMEH reported that approximately during 21-29 January, incandescent material was propelled up to 100 m above the summit and incandescent blocks rolled about 500 m S and SW down the flanks. During 26 and 29 January, incandescent blocks broke away from lava-flow fronts and rolled S towards the source of the Ceniza River.

INSIVUMEH reported that explosions from Fuego produced white and gray plumes that rose to an altitude of 4 km (13,000 ft) a.s.l. and drifted SW on 12 January. Incandescent material was propelled up to 75 m above the summit and incandescent blocks rolled W towards the Taniluyá and Santa Teresa ravines on 12 January and S towards the Ceniza ravine on 12 and 16 January. Based on information from the Tegucigalpa MWO and satellite imagery, the Washington VAAC reported that a faint plume was seen on 12 January drifting W.

INSIVUMEH reported that during 4-5 January, constant avalanches of incandescent material from Fuego's central crater and lateral crater (about 70 m from the S edge of the central crater) descended SW towards the Taniluyá River ravine. Several explosions produced shock waves and gas-and-ash clouds that reached altitudes of 4.2-4.8 km (13,800-15,700) a.s.l. Fine ashfall was noted in areas S and about 9-15 km SW of the summit.

INSIVUMEH reported that on 15 November lava flows from Fuego traveled about 150 m SW and avalanches occurred from the lava-flow fronts. On 17 November, three out of seven explosions propelled incandescent material 100 m above the central crater.

On 29 June, INSIVUMEH reported that pyroclastic flows from Fuego traveled mainly SW along the Ceniza River and a lesser number moved SW along the Taniluyá River. According to a news report, on 29 June an ash plume reached a height of 2.2 km above the summit (19,500 ft a.s.l.) and drifted W. On 3 July, explosions propelled incandescent material hundreds of meters above the central crater (~13,000 ft a.s.l.). Avalanches traveled ~300-500 m SW along the Ceniza River.

During 1-3 February, weak-to-moderate explosions occurred at Fuego. Shock waves from the explosions were sometimes felt in villages near the volcano. Small avalanches of volcanic material traveled down Fuego's S and W flanks.

Weak to moderate explosions continued at Fuego during 18-24 January 2006, sending dark gray ash plumes as high as 800 m (2,600 feet) above the crater. Explosion noises could be heard 25-30 km away. Incandescent lava ejections rising 100 m above the crater were seen on the night of 22-23 January that resulted in block avalanches down the SW flank.

During 4-9 January, moderate-to-strong explosions at Fuego produced ash plumes that rose to ~1 km above the volcano (or 15,600 ft a.s.l.). The explosions were accompanied by rumbling sounds and acoustic waves that shook windows and doors in villages near the volcano. Avalanches of volcanic material traveled down the volcano's SW flank.

An eruption began at Fuego on 27 December around 0545 and produced lava flows that traveled down Taniluya (SW) and Seca (W) ravines, initially extending ~800 m and 1,200 m, respectively. At 0602 a pyroclastic flow descended Seca Ravine, producing a S-drifting column of ash that rose to a height of ~2 km above the volcano (or 18,900 ft a.s.l.). Ash fell to the S of the volcano in the port of San Jose. Later that day, the lava flows reached lengths of 1.2 and 1.3 km, and pyroclastic flows traveled 1.8 and 2 km down the Taniluya and Seca ravines, respectively. Lava flows also traveled W toward Santa Teresa ravine, and SE towards Jute and Lajas ravines. A small amount of ash fell W and SW of the volcano in the villages of Panimaché (~7 km SSW), Morelia, Santa Sofía, and Los Tarros.

Volcanic activity continued through 28 December, with incandescent lava clots hurled ~75 m high, lava flows traveling down the volcano's flanks, and a dark gas-and-ash plume rising to ~1 km above the volcano (or 15,600 ft a.s.l.). Avalanches of volcanic material spalled from lava-flow fronts. On the 29th, lava only flowed in Santa Teresa ravine, reaching ~600 m. Moderate explosions continued through 3 January, depositing small amounts of ash in Panimaché village. According to a news article, none of the ~250,000 residents from the 78 communities near the volcano were evacuated.

On 27 December an eruption at Fuego produced an ash plume to a height of ~7.6 km (25,000 ft) a.s.l. that extended SSW and SSE of the volcano. The higher level ash (~7.6 km a.s.l.) drifted W to Honduras, while ash below ~6.1 km (20,000 ft) a.s.l. drifted E to the Pacific coast. According to news articles, two lava flows that were both ~2 km long traveled down the volcano's flanks, but posed no threat to inhabited areas. Articles also reported that about 25,000 local residents were put on alert, and emergency teams said that there was no immediate need for evacuations.

During 11-14 November, three lava flows were emitted from Fuego. On the 14th, two of the lava flows traveled from the S edge of the central crater 150 m toward the Ceniza ravine, and 400 m toward the Taniluyá ravine, and the third traveled 600 m W toward the Santa Teresa ravine. Avalanches of volcanic material spalled from the fronts of the lava flows.

A small eruption at Fuego on 17 July during 1715-1945 produced an ash plume that rose 3.5-4 km above the volcano's crater (or 23,800-25,500 ft a.s.l.). The eruption was accompanied by small pyroclastic flows that traveled SW down Santa Teresa and Taniluyá ravines.

A small eruption at Fuego on 17 July during 1715-1945 produced an ash plume to a height of 3.5-4 km above the volcano's crater (23,800-25,500 ft a.s.l.). The eruption was accompanied by small pyroclastic flows that traveled down Santa Teresa and Taniluyá ravines.

From 22-24 June, small incandescent lava expulsions reached ~50 m high and columns of grayish smoke rose ~300 m above the vent (13,300 ft a.s.l.) and drifted W. Weak rumbling and short avalanches of incandescent material accompanied these expulsions. On 27 June a lava flow was observed on the South flank extending approximately 300 m.

During 1-6 June, several explosions at Fuego produced low-level plumes. Small avalanches of volcanic material occurred on the S and W sides of the central crater. A lava flow, which began on 18 May on the volcano's W flank, extended ~1 km down the volcano's flank. On 2 June, a new lava flow was emitted that traveled ~120 m down Fuego's S flank.

During 17-20 May, lava flows continued to travel down Fuego's flanks, extending ~400 m W and ~500 m SW of the summit. Short avalanches originated from the lava-flow fronts. Also, explosions sent ash and incandescent volcanic material to low altitudes.

Small white plumes to ~200 m height were again observed during 11-17 May. Lava flows down the Santa Teresa and Taniluya ravines reached 700 and 500 m long, respectively, with avalanches originating from their fronts.

During 2-8 March, several explosions at Fuego produced plumes to a maximum height of 1 km above the volcano. Some explosions were accompanied by avalanches of volcanic material that traveled towards the Taniluyá (to the SW) and Santa Teresa ravines. Around 4 March, a lava flow traveled ~200 m down Fuego's SW flank. Blocks of lava spalled from the front of the lava flow.

During 24-25 January, several weak-to-moderate explosions at Fuego produced ash plumes to a maximum height of 1.5 km above the volcano. The eruptions were accompanied by avalanches of incandescent volcanic blocks towards several ravines.

On 22 December a narrow lava flow on Fuego's S flank reached a distance of ~200 m from the central crater. Many small block-lava avalanches traveled SW towards the Taniluyá River. The Washington VAAC reported that steam-and-ash emissions on 23 December rose to ~4.5 km a.s.l.

During 15-21 December, several small incandescent avalanches of volcanic material at Fuego traveled mainly SW toward the Taniluyá ravine. Around 20 December a narrow lava flow began to be emitted from the S edge of the volcano's central crater.

Several small explosions occurred at Fuego during 8-14 December, producing plumes that rose to ~600 m above the volcano. During the report period, small avalanches of volcanic blocks traveled towards Taniluyá, Ceniza, and Santa Teresa ravines.

There were several small explosions at Fuego during 1-7 December. During the report period, small avalanches of volcanic blocks traveled in the direction of Taniluyá and Santa Teresa ravines. On the evening of 2 December, a thin lava flow traveled about 100 m SSW of the central crater.

During 24-26 November there were several explosions at Fuego. On 25 and 26 November ash plumes from these explosions rose to low levels above the volcano. Incandescent lava was hurled ~100 m above the volcano and avalanches of block lava traveled towards the Taniluyá and Ceniza ravines.

During the report period, avalanches of incandescent volcanic material continued towards the Lajas and Taniluyá ravines on the volcano's SE and SW flanks. Small and moderate explosions expelled abundant incandescent lava to heights ~150 m above the crater. Some explosions generated rumblings, shock waves, and fine ash that was deposited on the skirts of the volcano. Near the end of the report period, the energy level of the eruption lowered, especially the flow of lava towards the Lajas ravine.

During 10-15 November, avalanches of incandescent volcanic material continued towards the major ravines on the volcano's flanks. Avalanches occurred from the fronts of the lava flows. Sounds like that of a locomotive or airplane turbine were heard emanating from the active crater. Small explosions expelled incandescent lava to heights of 75-100 m above the crater. Steam plumes from fumarolic activity reach heights of ~500-600 m above the crater, extending ~4-7 km to the S and SW.

During 3-5 November, avalanches of incandescent volcanic material traveled 600-800 m towards the Taniluyá and Ceniza ravines on the volcano's flanks. The avalanches originated from two areas about 20 m below the S edge of Fuego's crater. A few explosions produced low-level plumes. During an eruptive pulse beginning around 0026 on 7 November two lava flows were emitted. Avalanches occurred from the fronts of the lava flows. A ~30-m-high scoria cone was formed in the SW part of the central crater.

During 28-29 October, several weak explosions at Fuego sent plumes to a maximum height of 300 m above the volcano and volcanic bombs were sometimes thrown ~75 m above the volcano's crater. In addition, avalanches of incandescent volcanic material traveled ~600 m towards the ravine of the Ceniza River.

During 21-22 October, several weak explosions at Fuego sent plumes to a maximum height of ~300 m above the volcano. In addition, avalanches of incandescent volcanic material traveled towards the ravines of Taniluyá and Ceniza on the volcano's flanks. The avalanches originated from two areas about 20 m below the S edge of Fuego's crater.

During 14-18 October, several weak explosions at Fuego sent plumes to a maximum height of 800 m above the volcano and volcanic bombs were sometimes thrown 75-100 m above the volcano's crater. In addition, avalanches of incandescent volcanic material traveled towards the ravines of Taniluyá, Ceniza, and Trinidad on the volcano's flanks.

During the evening of 9 October, a narrow lava flow traveled ~800 m down Fuego's SSW flank towards the head of the Taniluyá River. A small sustained lava fountain reached ~75 m above the volcano during the evening of 10 October. On 12 October, a narrow lava flow traveled ~400 m from an area about 20 m below the S edge of the crater. Small avalanches occurred from the lava-flow fronts. Six explosions produced plumes to ~600 m above the volcano's summit. A small lahar traveled towards the Zanjón Barranca Seca Ravine.

Weak explosions at Fuego on 21 September produced white plumes to ~200 m above the volcano. During 25-26 September, several moderate explosions emitted incandescent lava bombs to heights of ~150 m and plumes to 600-900 m above the volcano. The explosions were accompanied by avalanches of volcanic material that traveled W to the head of Santa Teresa Ravine.

Ten explosions on 16 September sent ash columns ~400-600 m high; three ejected incandescent lava and caused block avalanches. White fumarolic plumes typically rose 300-500 m. Similar activity was observed through the 20th. Overnight on 19-20 September weak incandescence was seen from the crater. The highest plume during this period rose ~900 m.

During 8-13 September, small explosions at Fuego produced low-level plumes and avalanches of volcanic blocks traveled down the volcano's flanks. On 12 September a small lahar occurred down the volcano's flank.

During 2-3 September, small explosions at Fuego produced low-level plumes and avalanches of volcanic blocks traveled down the volcano's flanks. On 4 September a small lahar flowed down the volcano's S flank, partially blocking a road.

During 18-23 August, many weak-to-moderate explosions occurred at Fuego. The explosions expelled lava blocks to ~100 m above the crater and plumes rose to a maximum height of 0.5 km above the crater. Avalanches of incandescent volcanic material traveled to the mouths of several ravines on the volcano's flanks.

During 11-16 August, dozens of weak-to-moderate explosions occurred at Fuego. The explosions expelled lava blocks to ~75 m above the crater and plumes rose to a maximum height of 1.2 km above the crater. Avalanches of incandescent volcanic material traveled to the mouths of several ravines on the volcano's flanks.

A series of strong explosions at Fuego on 21 July during 0630-0950 produced ash plumes to a height of ~2 km above the volcano. Plumes traveled W, SW, and S, depositing ash in several villages near the volcano. Small incandescent avalanches of volcanic material traveled to the mouths of several ravines. Ash emissions and avalanches continued through 27 July.

On 7 July, an explosion from Fuego generated an avalanche of lava fragments near the headwaters of Santa Teresa ravine. Forty-three weak to moderate explosions were observed during 10-11 July; the explosions produced ashy plumes less than 2 km above the ground that were blown west-southwest at least 20 km from the volcano.

During 1-6 July, small explosions at Fuego produced plumes to ~1.4 km above the volcano that predominately drifted SW. Occasional avalanches of volcanic material traveled down ravines flanking the volcano.

On 1 June, five moderately strong explosions occurred at Fuego with gas-and-ash plumes rising up to 2 km above the summit. Incandescent avalanches of material from these explosions occurred in the Santa Teresa and Río Taniluyá ravines. This pulse of activity was preceded by half an hour and followed by two hours of explosions producing steam plumes rising up to ~0.5 km above the summit. On 6 June, frequent small explosions produced gas plumes that rose to ~0.5 km above the summit and less frequent explosions produced gas-and-ash plumes that rose to ~1.0 km above the summit. Incandescent avalanches from these explosions occurred in the Santa Teresa and Ceniza ravines. A hot lahar, followed 45 minutes later by a smaller lahar, occurred in the Zanjón Barranca Seca ravine on 6 June. Moderate explosions continued on 7 June, producing small gas-and-ash plumes to ~0.5 km above the summit.

During 31 May to 1 June moderate volcanic and seismic activity continued at Fuego, with several explosions producing ash plumes. The highest rising plume reached ~1.5 km above the volcano on 31 May. This explosion also produced avalanches of volcanic material down the ravines of Taniluyá and Santa Teresa.

During 18-21 May, moderate volcanic activity continued at Fuego. Several explosions produced ash plumes, with the highest one reaching ~1.2 km above the volcano on 20 May. On 21 May, avalanches of incandescent volcanic material traveled toward the ravines of Seca (to the W) and Taniluya (to the SW).

During 10-17 May, moderate volcanic activity continued at Fuego. Several explosions produced ash plumes, with the highest one reaching ~1.8 km above the volcano on 13 May. Explosions on 13 May at 0411 and 0618 emitted incandescent volcanic material ~150 m. In addition, a lahar traveled W toward Seca Ravine.

During 28 April to 4 May, explosions at Fuego produced gas-and-ash clouds. On 28 April, an explosion produced an ash plume to ~1.5 km above the volcano, and ash was deposited ~4 km SW of the volcano in the villages of Panimaché I and Panimaché II. In addition, a small avalanche of volcanic material traveled W toward Santa Teresa Ravine.

On 12 April weak-to-moderate explosions at Fuego produced plumes to 0.3-1 km above the volcano. Lava flowed 75-100 m from the central crater and avalanches of volcanic material traveled as far as 400 m towards Santa Teresa and Taniluyá ravines.

During 31 March to 6 April, weak-to-moderate explosions continued at Fuego. The highest rising ash plume produced from the explosions reached ~1.2 km above the volcano on 5 April and drifted SSE. Lahars flowed down Seca Ravine on 30 March, and near the village of Sangre de Cristo on 3 April. During the report period, incandescent avalanches of volcanic material traveled down several ravines, including Santa Teresa, Ceniza, and Taniluyá.

During 24-30 March, sporadic weak explosions and three strong explosions were recorded at Fuego. On 26 March a strong explosion produced an ash plume that reached ~1 km above the vent and caused incandescent avalanches in the Zanjón Barranca Seca and Trinidad ravines. On 29 March two explosions within 7 minutes produced gas-and-ash plumes that reached heights of ~1 km above the vent. A lahar occurred on 29 March in the Zanjón Barranca Seca ravine.

During 16-23 March moderate-to-strong explosions continued at Fuego, producing ash plumes to a maximum height of 1.3 km above the volcano. On 16 March ash fell in the village of Morelia. Explosions during 17-19 March produced incandescent avalanches of volcanic material that traveled down the Seca Ravine. During the report period, ash fell in the village of Sangre de Cristo.

During 9-15 March, moderate-to-strong explosions continued at Fuego, producing ash plumes to a maximum height of 1.7 km above the volcano. Incandescent avalanches of volcanic material traveled as far as 600 m down ravines on the volcano's W, SW, and S flanks and ash fell in villages from Sangre de Cristo to Panimaché.

During 4-8 March, moderate-to-strong explosions at Fuego produced plumes to ~1.5 km above the volcano. On 5, 7, and 8 March avalanches of incandescent volcanic material traveled as far as 1.5 km down several ravines, including Seca, Taniluyá, Ceniza, and Trinidad. Explosions on the 7th and 8th deposited ash 6-10 km from the volcano, including in the villages of Sangre de Cristo and Panimaché.

During 25 February to 2 March weak-to-moderate explosions continued at Fuego, producing plumes to ~1.7 km above the crater. Avalanches of volcanic material traveled down several ravines, including Trinidad, Ceniza, Santa Teresa, and Taniluyá (to the W). Explosions on 28 February deposited small amounts of fine ash in the village of Sangre de Cristo, and explosions on 29 February deposited ash W and SW of the volcano in the villages of Yepocapa and La Cruz.

During 18-19 February, several moderate-to-strong explosions at Fuego produced ash plumes to 0.8-1.5 km above the crater. The explosions also produced landslides of incandescent volcanic material that traveled down several ravines: Seca (to the SW), Taniluyá (to the W), Trinidad, Ceniza, and sometimes towards Las Lajas-El Jute. Small amounts of fine ash were deposited to the W in the village of Sangre de Cristo. On 22 and 23 February explosions continued, sending plumes to 1.8 km above the crater. Ash fell in the communities of La Rochela, Ceilán, El Zapote, and Guadalupe.

INSIVUMEH reported that during 11-16 February several moderate-to-strong explosions occurred at Fuego, producing gas-and-ash plumes to 1.6 km above the crater. Incandescent avalanches traveled a maximum distance of 1 km down several ravines, including Trinidad and Taniluyá to the SW, Seca to the W, Ceniza, and Lajas. During 11-12 February, ash fell in the villages of Panimaché and Sangre de Cristo. According to the Washington VAAC, on 14 February ash was visible on satellite imagery at a height of ~3.5 km above the volcano.

Explosions at Fuego on 8 February produced incandescent avalanches that traveled toward the Seca (to the W), Trinidad, and Taniluyá (to the SW) ravines. Several moderate-to-strong explosions on 9 February produced ash-and-gas plumes that rose to heights of 800-1,500 m above the volcano and drifted W and S. Ash fell as far as 15 km from the volcano, including in the town of Sangre de Cristo and in several ranches (locally termed fincas) in the area. According to the Washington VAAC, on 9 and 10 February small ash plumes were visible on satellite imagery.

During 28 January to 2 February, small-to-moderate explosions occurred at Fuego. The highest rising ash plume was produced from an explosion on 29 January. The plume reached ~1.1 km above the crater and was accompanied by avalanches of volcanic material down Barranca Seca. A small amount of ash fell in Panimaché village and possibly in Santa Sofía. On 31 January two small collapses in the S edge of the central crater produced small avalanches of lava blocks.

An ash emission from Fuego on 8 January around 1500 rose to ~3 km above the volcano. According to news reports, 25-30 explosions occurred per minute and were accompanied by loud rumbling noises. No evacuations were ordered. Plumes and a relatively strong hotspot were visible on satellite imagery.

During 10-16 December, weak explosions at Fuego continued to produce ash clouds that rose 200-1,000 m above the volcano. Explosions and avalanches on 16 December sent volcanic material W and SW towards Taniluya and Santa Teresa ravines. Civil Aeronautics recommended that airplanes avoid the area near the volcano due to ash in the atmosphere.

During 7-9 December, moderate to strong explosions at Fuego expelled ash up to 0.5 km above the crater. The ash was distributed to the N. Incandescent avalanches were observed in the Santa Teresa and Taniluyá ravines.

During 28 November to 1 December, moderate-to-weak explosions at Fuego produced gas-and-ash plumes to heights of 700-900 m above the volcano. The explosions were accompanied by avalanches of volcanic material that traveled towards Teresa, Taniluyá, and Trinidad ravines. On the evening of 1 December, incandescence was seen in the ravines and in the active central crater. During the report period, continuous harmonic tremor was recorded.

Small explosive eruptions at Fuego produced gas-and-ash plumes up to 1.2 km above the crater. During the night of 18-19 November moderate-sized avalanches were observed in the upper Santa Teresa and Trinidad ravines. Night-time incandescence at the summit was common during the week. Periods of harmonic tremor, lasting between 0.5-3 hours, were recorded on 23 November, and almost continuous harmonic tremor was recorded for a period of 21 hours on 24 November.

A 33-minute-long explosive eruption began at Fuego on 17 October at 0007, producing a gas-and-ash plume to ~1.5 km above the crater. This eruption was preceded and followed by small explosions and seismicity. During one of these earthquakes a small incandescent avalanche descended the Santa Teresa ravine.

Ash plumes emitted from Fuego were visible on satellite imagery on 28 September. The first emission occurred around 0500 and produced an ash plume that covered an area of 5 x 5 km and drifted S. It was no longer visible by 0800. A second ash emission between 0815 and 0832 rose to ~ 6 km a.s.l. Ash was no longer visible on satellite imagery by 1445.

INSIVUMEH reported to the Washington VAAC that on 9 July at 0530 Fuego's lava dome collapsed, producing pyroclastic flows. After the collapse, strong explosions sent ash to ~2 km above the volcano's summit. Ash clouds drifted W and ash fell in communities W and SE of the summit. An ash cloud was visible on satellite imagery.

INSIVUMEH reported that the eruption at Fuego on 29 June during 1745-2200 consisted mainly of lava flows and avalanches of volcanic material traveling down the volcano's E flank. Incandescence was visible from the city of Antigua and the S coast. Ash fell in villages W and SE of the volcano, including San Pedro Yepocapa. Explosions and tremor were recorded by a seismic station. After the eruption, weak-to-moderate explosions at Fuego produced ash clouds to ~900 m above the volcano and seismographs mainly recorded tremor. Pyroclastic-flow material extended ~1.5 km down the volcano's W flank. Fuego was at Alert Level Yellow and pilots were advised to avoid flying near the volcano.

Based on information from INSIVUMEH, the Washington VAAC reported that a moderate eruption began at Fuego on 29 June at 1700. Lava flows were seen, and ash fell S and SW of the volcano. As of 30 June lava flows were still visible, an ash plume was W of the summit, and seismicity was at low levels. Both days a hot spot was visible on satellite imagery, but an ash cloud could not be distinguished from abundant meteorological clouds in the area.

At the end of April U.S. Air Force meteorologists used GOES-12 imagery to describe a thin plume of Fuego's ash that rose to ~7 km a.s.l. and blew SW at 20-30 km/hour. The ash plume was visible for over an hour. On 2 May the Washington VAAC reported that Fuego discharged small eruptions, with most ash remaining near the summit and little if any ash clearly visible on satellite imagery.

The Washington VAAC reported that on 28 April Fuego produced intermittent ash eruptions. One cloud was observed at ~ 7 km a.s.l., traveling SW at 19-29 km per hour. Although remote sensing was complicated by poor visibility due to high cirrus clouds and smoke from fires, some eruptive puffs remained recognizable when they blew over the coast.

INSIVUMEH reported that as of 19 January moderate eruptions continued at Fuego that produced ash clouds to 2 km above the summit. Ash drifted to the S and SW, depositing fine ash in the areas of Rocela, Panimache, and Palo Verde. In addition, incandescent avalanches traveled down canyons on the volcano's flanks.

The Washington VAAC reported that an eruption began at Fuego on 8 January around 0500. According to INSIVUMEH, as of 1100 that day the eruption continued with ash explosions and lava flow emission. A steam-and-ash column rose 5.7 km a.s.l. and drifted to the W. In addition, two small-to-moderate pyroclastic flows traveled down the drainage of the Santa Teresa River Valley. CONRED stated that the Alert Level was raised to Orange and several people were evacuated from the town of Sangre de Cristo. According to a news report volcanism decreased the following day, so the Alert Level was lowered from Orange to Yellow.

An explosive eruption and partial crater collapse occurred at Fuego on 26 December around 0905. An ash cloud was generated that reached ~2 km above the volcano and drifted W toward the Yepocapa region. Neither damage nor injuries were reported.

A new cycle of eruptive activity began at Fuego on 16 July that consisted of an increase in Strombolian explosions and the occurrence of high-frequency volcanic tremor for 24 hours. On 28 July a thick gray ash cloud extended 10-15 km in length and drifted to the W. Ash was deposited in the areas of Rochela, Panimaché, Morelia, Santa Sofía, Yepocàpa, and Chimaltenango. This activity was associated with the collapse of the front of a lava flow, which began on 23 January. On 29 July an increase in seismic activity was recorded, the energy of explosions in the crater increased, and there was a 2- to 3-km-long lava flow. On 2 August explosions changed from Strombolian to Vulcanian, ash columns rose 800-1,400 m above the crater, and avalanches of volcanic blocks traveled down the volcano's flanks. The same day, gas emission from the crater decreased significantly, and the SE lava flow did not travel as quickly as it had previously.

Volcanism increased at Fuego on 12 February, with a ~2-km-long lava flow streaming down its flank towards an unpopulated area. Several shelters have been set up in case lava flows travel towards populated areas or volcanism increases. The volcano remained at Alert Level Yellow.

Based on information from INSIVUMEH, the Washington VAAC reported that on 1 February at 0930 ash, steam, and lava were emitted from Fuego. An ash-and-steam cloud rose to ~4.5 km a.s.l. and drifted to the SW. No ash was seen on satellite imagery, but a hotspot was visible on infrared imagery.

Observations in late January revealed that Fuego was erupting a lava flow down its E flank. The flow stretched several hundred meters below the summit before falling apart on steep slopes. The toe of the flow calved off about once a minute, but the volume of material was not sufficient to generate pyroclastic flows. No explosive activity was observed and only low-level tremor was recorded. Coordinadora Nacional para la Reducción de Desastres (CONRED) and INSIVUMEH are monitoring the situation at the volcano.

An eruption began at Fuego on 4 January during 0200-0300. A probable explosion was followed by Strombolian-type ejections and continuous tremor. No lava flows were visible. Until at least 9 January intermittent mild-to-moderate explosions produced ash clouds that rose 400-600 m above the cone.

The Washington VAAC reported that a small eruption at approximately 1645 on 9 December sent ash to ~ 4 km a.s.l. (near-summit level). The small ash cloud drifted to the W and NW, was initially dense, and rapidly dissipated so that it was no longer visible on satellite imagery by 2345. Throughout the day, occasional strong hot spots were visible on GOES-8 multi-spectral imagery. According to the Washington VAAC, on the evening of 9 December a volcanologist with INSIVUMEH in Guatemala stated that Fuego had shown increased instability with several explosions. The last reported eruption of Fuego sent ash to ~4 km a.s.l on 29 August 2000.

Information is preliminary and subject to change. All times are local (unless otherwise noted)

September 1971 (CSLP 85-71)

R. Stoiber telephoned the following report on 17 September. "A sudden, violent ash eruption and possible lava flow occurred at Volcano Fuego on 14 September 1971. At present, there is a white steam cloud only. An investigation is underway."

Fuego . . . has renewed activity and is spurting ashes and large amounts of lava. In view of this renewed activity, observation posts have been set up so authorities can take the proper measures for the evacuation of settlers close to the volcano in Scruintla Department. The lava flow was heading toward the Morelia Santa Sofía Farm and others are also threatened. Last week, this volcano spewed out large amounts of ashes and sand, causing damage to the plantations of several departments, but the population of San Pedro Yepocapa was the most affected. Two persons were killed there.

The following report from Samuel Bonis was telephoned to the Center today by R. Stoiber. "Volcano Fuego eruption: Sudden start 1445, 14 September 1971. Stopped 0300 15 September 1971 directed toward Yepocapa (SW wind). Tremors felt during eruption in Alotenango and Yepocapa. Very fine ash (powder) fell toward Alotenango. However, hot rocks and boulders came down the Barranca Honda toward Alotenango and reached La Reunión next to the Finka Capetillo.

"People called this lava but really it was a hot mixture of ashes and boulders. Coarse sand and gravel fell on Yepocapa more or less 8 km W of the crater to a depth of 30 cm. 5-cm-diameter scoria also fell here. Ash fell in Tapachula on the Mexican border and also was reported in Quezaltenango and in San Marcos.

"Rough calculations from Guatemala City by experienced geodocist estimates flowing molten material was thrown up to 1,000 m above the crater—black ash cloud much higher. All observers agree this was the most spectacular eruption in memory (at least 70 years). I don't think any lava flows produced; summit crater somewhat modified. Current activity minor or variable white vapor from summit crater. One killed and ten percent of the houses in Yepocapa with roofs caved in from the weight of the ash."

March 1973 (CSLP 24-73)

Fine ash from February-March eruption falls in a 70-km radius

Card 1573 (01 March 1973) Ash column rises to height of 12 km on 22 February

The following report was received by R. Stoiber from Samuel Bonis on 28 February. "22 February Fuego started throwing fine ash to a height of about 12,000 m. This was accompanied by ash flows down the Barranca Honda. Activity continues. Prior to this there has been almost continuous gentle steam emission since the strong September 1971 eruption."

Card 1583 (16 March 1973) Ashfall in a 70-km radius during February-March eruption

The following report was received by R. Stoiber from Samuel Bonis on 15 March 1973. "Volcano Fuego erupted from 22 February to 3 March 1973. Most of the activity occurred between 23 February and 1 March. Fine ash was blown in a 70 km radius to the W, S, and E. Maximum thickness on the lower slopes of the cone was 1.5 cm. Voluminous ash flows came down canyons on the SW, S, and E slopes. There was no major damage."

October 1974 (CSLP 134-74)

Strong eruptions and heavy ashfall

Card 1955 (15 October 1974) Strong ash eruptions on 14 October

The Fuego volcano renewed its activity at 0400 on 10 October 1974, with tiny eruptions of ash and flows from the summit crater. Activity increased markedly at 0200 on 14 October, with very strong ash eruptions. Further investigations are underway.

"The Fuego volcano renewed its intensive activity on 14 October at 0200. Ash clouds were thrown about 7 km above the vent. SE winds deposited 33 cm of ash 9 km to the W and 5 mm were deposited 60 km away. Traces of ash were carried to the Mexican border 150 km away. A preliminary estimate for the volume of ash is 0.1 km3 as of 20 October. Voluminous hot ash flows rushed down the canyons on all sides of the cone, especially Barrancas Honda, Las Lajas, Jute, Ceniza, and Santa Teresa. A renewed eruption lasted from 2145 on 17 October to 0030 on 18 October. Volume of ash from this eruption will probably prove to be greater than the 14 October episode. Field investigations are continuing.

"Thousands of people have abandoned their homes and many roofs have caved in from the weight of the ash. Communications and roads are disrupted. This year's crops over a large area have been destroyed and grazing areas have been buried. Although there have been few casualties, the eruption will take its unpublicized toll when malnutrition takes effect."

"Volcano Fuego continues in activity with generally gentle steam and light ash emissions, punctuated by strong ash eruptions on 13, 17, 19, and 23 October. Ash has been carried at least 200 km to the N and W. Ten centimeter lithic fragments were thrown 5.5 km to the SW by a one-hour episode on the 23rd, depositing 5 cm of ash 9.5 km to the SW.

"Major ash flow activity has decreased. The intermittent strong blasts, especially the showers of lithic fragments, have driven off many of the strong-hearted who had remained behind to clean their roofs and care for their livestock. Many crops have been ruined as far as 100 km to the NW. If this eruption follows past patterns, it should diminish in intensity. Field investigations continue."

December 1974 (CSLP 171-74)

"In mid-November bluish ashen daylight skies and beautiful twilight glows were noted over Baja, California and southern Arizona. The dust stratum is probably from the continuing November eruption of Fuego in Guatemala." (excerpt from note submitted to Science by A.B. Meinel and M.P. Meinel, University of Arizona, Tucson).

Since 26 November ultracirrus has been seen near Boston around sunset, attaining a pinkish color about 15 minutes after sunset. At dusk on 6 December and especially at dawn on 7 December the sky became glowing red and measurements indicate twilight conditions as after the Agung eruption of 1963. In Puerto Rico the sky radiance at 0.7 microns was higher at 3.5° solar depression than at 2° solar depression. Pilots observed a dust layer at about 20 km and a similar height was measured by LIDAR at NASA Langley (Applied Optics, January 1975).

As after the eruptions of Krakatau in 1883 and after Agung the dust may overspread the northern hemisphere, terminating a period of clean stratosphere, and abate within two to three years.

January 1975 (CSLP 171-74)

On 28 and 29 December 1974, a "volcanic dust sunset" was observed by Dr. Lamb at Ketteringham (52°34'N, 01°12'E), England. In particular, the purple patch and other colors of the background sky were observed at the proper elevations (cf. figure 1(b), p. 433, Philosophical Transactions of the Royal Society, vol. 266, No. 1178 of 1970, and the Krakatao 1883 Royal Society Report). The timing on 28 and 29 December was about 40-60 minutes after sunset, which places the illuminated layer at around 22 km height. This is the first time Dr. Lamb observed these optical effects since some time in 1964 when they were last visible in the United Kingdom after the Bali eruption. A colleague at the same institution noticed the same effects independently of him.

"The sky around the sun appeared abnormally white when the sun was at a slightly higher elevation, both in the morning and in the evening on the days concerned. On 28 December the rising moon was also abnormally white, although the sky was clear, and the background sky had an unusually leaden hue (purplish dark gray rather than black) for some hours. Such effects were hardly discernable on 30 December and thereafter. Hence, we are not (or not yet) discussing a uniform veil of material in the stratosphere."

Information Contacts:H.H. Lamb, Climatic Research Unit, University of East Anglia, Norwich, England.

August 1975 (CSLP 134-74)

Sporadic explosions and ashfall through 4 August

Card 2263 (25 August 1975) Sporadic explosions and ashfall through 4 August

On 28 May 1975, trace amounts of fine ash fell on Yepocapa, 8 km W of Volcan Fuego. The activity started at 0800 hours local time and ended during the night. This gentle eruption was probably accompanied by small ash flows on the upper southern slope of the cone.

Sporadic explosions have been heard coming from the summit crater during the period 23 July to 4 August. Small possible sah flows were reported on 29 July. The summit of the cone has been clouded for most of these months so that continued small ash flow activity cannot be confirmed. A stronger explosion accompanied by shock tremor was felt in Yepocapa at 2130 hours on 30 July.

On 4 August a tiny trace of ash powder fell on Yepocapa during the morning, starting at about 0800 hours. This was accompanied by a strong sulfur odor and columns of vapor shooting out of the crater. A red glow was seen in the crater region at dawn. Strong explosions were heard at about 1000 and 1500 hours, the latter accompanied by shock tremors. Apart form continuous vapor emission, this has been the only activity since the major eruption of October-November 1974. There has been no unusual activity since 4 August 1975.

Unusual activity on Fuego, aside from minor vapor emissions, started the night of 19 September. Since that time there have been occasional emissions of dark gray to black ash clouds. The ash was either dissipated as dust in the atmosphere or fell on the upper slopes of the cone. A trace fell on some populated areas but was insufficient for collection. A large ash cloud was observed on 2 October at 0830, and on 11-12 October ash, brownish-gray in color, fell on Antigua.

On 3 March, a steam plume was emitted for 5-10 minutes from a vent about 200 m below the summit crater on the S flank. The plume first appeared to be dust-colored then turned white. About 2 weeks earlier, road workers on the N flank had reported a small saline brook originating below the summit crater.

Steam clouds containing a little ash rose about 1,000 m above the summit, beginning before dawn on 11 September. The eruption was preceded by felt earthquakes on 6 September at 2206 and 9 September at 0420 and was accompanied by harmonic tremor. On 12 September, emission of voluminous brown to black clouds was nearly continuous, frequently broken by 10-20-second intervals of quiescence. At 2130, incandescent bombs and ash were ejected. Ash emission was continuous on 13 September and harmonic tremor amplitude increased. Some ash fell on the W flank, at Yepocapa. The eruption had ended by 14 September [but see 2:10].

Steam and ash emission has continued intermittently through late October. A substantial increase in activity 19-20 October was reported. Columns of dark gray ash were ejected at about 1-hour intervals on 24 September, accompanied by rumbling. Activity declined the next day but similar ash ejections resumed on 26 September, lasting until evening. At 2000, loud rumbling was succeeded by a small eruption of incandescent ash and bombs, accompanied by hot avalanches that moved a short distance down canyons on the upper flanks. Persons near the volcano felt an earthquake 2 hours after the eruption and several more the next day. Incandescent ash was ejected on 28 September until 2200 and thick ash, accompanied by loud explosions, was emitted for several hours the next day. A moderate ash eruption, including small hot avalanches, was visible through thick cloud cover on 2 October. Two days later, several explosions at around 1630 produced black ash clouds. About 3-4 brown to black ash puffs per hour were reported on 7 October, accompanied by a red glow at night. Incandescence was also reported during the night of 9 October.

Explosions increased markedly on 19 October, producing minor local ashfalls from clouds that rose 1,500 m above the vent, and continuous small hot avalanches, which were again restricted to canyons on Fuego's upper slopes. Maximum activity was on 20 October, when a trace of ash fell on villages SW of the vent. Intermittent small steam, ash, and ash flow eruptions continued on a reduced scale as of 26 October.

Increased activity was continuing in mid-November. Only occasional observation of the volcano has been possible because of heavy cloud cover. 29 October: Weak ejection of incandescent material at 2230; no hot avalanches observed. 3 November: Emission of large volumes of steam under considerable pressure. 5 November: Moderate steam emission from the summit crater and a thin, 60 m high steam column issued from a vent high on the NE flank. 7-9 November: Weak steaming from both vents 7 November, increased slightly on the 8th. Ash ejection 9 November was mainly from the summit crater. 12 November: Steam and ash emission from the summit crater and steaming from the NE vent. 13 November: Intermittent 250-300 m steam and ash clouds from the summit crater during the day. Between 1915 and 1930, bright red incandescent material was ejected. 14 November: Steaming during the morning, succeeded by intermittent ejection of dark gray and black ash in the afternoon. 15 November: Steam emission from the summit crater, and clouds of steam from the upper portion of a canyon on the E flank, possibly from a fresh hot avalanche deposit. 16 November: Weak felt earthquake at 1455, accompanied by noise. 17 November: Intermittent bursts of dark gray and black ash from the main crater visible during the morning.

Cloudy weather continued to hamper observations through December, but black ash emission was frequently visible during the day and glow or small incandescent eruptions at night.

Brief, intermittent ejection of black ash occurred 20 November and was occasionally visible through clouds 24-28 November. Weak glow during the night of 20 November brightened the next night and was weak again on 22 November. Felt earthquakes on 23 November preceded incandescent tephra ejection during the night.

On 29 November, activity had declined to steaming within the crater without night glow, which persisted until the afternoon of 2 December, when felt earthquakes preceded black ash ejection. Intermittent, 5-minute incandescent eruptions were seen that night and more ash was ejected the next morning. Glow was seen on 6 December and weak black ash emission was occasionally visible through the 9th.

Visibility was poor during the next 10 days. Black ash was seen on 12 and 14 December, but the volcano was only steaming on the 17th. A glow was observed on 18 December and intermittent black ash puffs were seen during the next 3 days. Ash clouds rose more than 650 m above the crater during the mornings of 22 and 23 December, but activity had weakened by the afternoon of the 23rd. On 24 December, 200-m ash clouds were emitted in the afternoon and there was a glow in the crater at night. The next day, intermittent ash puffs reached 600 m above the crater and incandescent eruptions, accompanied by a small glowing avalanche, occurred at night. Ash puffs continued through 28 December, and small incandescent eruptions were seen that night.

Intermittent activity continued through late January culminating in the largest eruption since 1974. The 29 December-28 January information is from Paul Newton, and the 29 January-1 February information was reported by Samuel Bonis to Richard Stoiber.

29 December-15 January: Black (primarily) to gray ash clouds were emitted at low velocity from at least 3 vents within the summit crater. Ash fell mainly on the upper N flank, but some fine material fell several kilometers downwind. Incandescent ejecta was visible above the summit on 30 December, and l, 5, 7, 9, and 15 January. Incandescent activity was weak except on the 15th, when bombs were ejected and ash fell on the E flank. Weak steaming from a small vent on the upper E flank was observed on 9 January. 16-17 January: Mostly steaming, with a little black ash emission. 18-22 January: Low-velocity black ash emission to a maximum height of about 370 m above the crater. 23-28 January: Activity decreased markedly to weak steam emission.

Weak earthquakes, accompanied by rumbling, were felt at 2015 on 29 December, 2130 and 2200 on 5 January, between 1100 and 1115 on 9 January (2 events), 1100 and 1215 on 15 January (lasting about 4 seconds each), and 0600 on 20 January (followed by black ash emission). Larger events were felt on 19 January at 2015 (15 seconds) and 2320 (about 4 seconds).

"Fuego had its strongest eruption since 1974 from 29-31 January. The eruption column reached about 4000 m above the crater, and 1 mm of ash blanketed the ground 5 km SW of the vent. Small nuées ardentes flowed down the canyon of the Rio Taniluya, on the SW flank of the volcano. Fuego was inactive at sunrise on 1 February."

More prominent Vulcanian activity 28-31 January was followed in February by a lava flow, uncommon in Fuego's history. Since Fuego's first recorded event, in 1524, less than one in four eruptions have been accompanied by a lava flow.

The following information, provided by Paul Newton, supplements the report last month. Weak glow in Fuego's summit crater was observed at 1800 on 28 January, beginning 3 days of strong explosive activity. By 2000, bright orange-red incandescent material could be seen in the crater and glowing avalanches flowed down the flanks, accompanied by large incandescent blocks. The next day, black to gray-black ash was emitted steadily to several hundred meters above the crater. Strong, low-pitched rumbling was heard and a few weak felt shocks occurred. At night, glowing avalanches were again visible and incandescent material rose a short distance above the crater rim. On 30 January, frequent strong rumbling accompanied emission of black to gray-black ash to an estimated height of 2,300 m above the crater. After sunset, incandescent ejecta including large light orange to bright red blocks rose as much as 250 m above the crater and large glowing avalanches flowed down the flanks. The eruption began to weaken after dawn on the 31st. Ash ejection had become intermittent by 1630 and had stopped by 2200. Crater glow had dimmed to a dull red. The next morning, activity was limited to emission of a small brown-white to white plume.

The following is a report by William I. Rose, Jr. "Throughout February, Fuego has been repeatedly visited by a plume-sampling aircraft from NCAR. Lava flows were first observed on 9 February in two 30 m-diameter craters 0.1 km SW of Fuego's summit. The flows had advanced 0.5 km down the SW flank of the cone by 11 February and the lava craters showed continuous incandescence. Hot debris slides from the toes of the two flows had cascaded more than 3 km down the valley of the Río Taniluya by 22 February. Small (100-500 m-high) ash eruptions (3-15/hr) occurred from the summit crater as the lava flow activity continued. On 24 February the three vents were observed in simultaneous activity. The summit crater was erupting a continuous stream of gas and fine ash, while the two lava vents exhibited lava fountaining interspersed with dark ash explosions. The rate of lava flow extrusion appeared to be increasing."

Emission of black to gray ash continued through March. Cloudy weather prevented observations on 9 days during March, and no report on the lava flows was available. Intermittent incandescence was seen during the evening of 26 February, but no incandescence has been observed since then. Activity was limited to weak steaming on 28 February and 22, 25, 27, and 29 March.

Strong activity occurred on 25 February, and 2, 4, 23, and 30 March. Ash columns rose about 1000 m above the summit at 1700 on 25 February, and from 0600 until clouds obscured the volcano at 1100 on 2 March. On 4 March, black ash was emitted to 1250 m above the vent for over 3 hours, beginning at 0600, but the column had become lighter colored by 1100 when clouds prevented further observation. Between 0730 and 1030 on 23 March, fine ash and vapor reached 1800 m above the vent, while heavy ashfall occurred on the upper N flank. At 0600 on 30 March, emission of black ash from the main crater was accompanied by a vapor plume from the N vent. Shortly before 0800, a 2300-m black column was emitted, appearing to originate from both vents, and a hot avalanche flowed down a canyon on the E flank. The eruption could be seen above the clouds until 1100, when visibility became completely obscured.

Earthquakes were felt in Antigua, 17 km NE of Fuego, on 4 March at 0550 (moderately strong) and 1137 (weaker); 13 March at 0130 (weak); 22 March at 0340 (weak); and 30 March at 1330 (strong, lasting 4 seconds).

Emission of black to gray ash continued through late April. Clouds and haze completely obscured the volcano on 9 days during April and limited visibility to only a few hours on most other days.

Activity usually consisted of mild to moderate emission of gray ash. Stronger activity occurred on 2 April, when black ash rose about 1000 m during the morning, but activity had declined by late afternoon. Dark gray ash emission was visible between 0730 and 0830 on the 20th (to 1000 m above the summit) and at about 1030 on the 23rd (to 550 m). Small amounts of fine ash fell on Antigua on 17, 18, 19, 21, and 25 April. Incandescence was seen before dawn on 15 and 20 April.

At 1120 on 15 April an earthquake centered approximately 15 km NE of Fuego was felt at intensity 3 in Antigua, 3 km from the epicenter, for about 10 seconds. A small 1.5-second event was also felt in Antigua at 1822 on 26 April.

Intermittent emission of gray to black ash clouds continued through late May. Clouds and dense haze totally obscured the volcano for 11 days of the 25-day reporting period (28 April-22 May), and visibility was limited to only a few hours on many other days.

Small incandescent eruptions occurred after sunset on 3 May, the only incandescent activity seen during the reporting period. Fine ash fell in Antigua on 7 May, then after 2 days of weak steam emission (8-9 May) and a cloudy day (10 May), ashfall in Yepocapa, 8.5 km NW of the summit, was reported on the 11th and 12th. Ash rose to more than 1400 m early on 13 May and to about 1100 m the next day, when simultaneous activity from 3 vents was observed and several small directed blasts from a fourth vent sent hot avalanches down a canyon on the SE flank. Ash fell on Antigua each day between 15 and 20 May, but the volcano was visible only for brief periods; maximum observed ash cloud height was about 1500 m, at 0900 on the 18th. Only 1 earthquake was felt in Antigua during the report period, a small shock at 1145 on 5 May.

A column of incandescent ejecta was seen above the summit after sunset on 22 May, but observed activity declined between 23 and 28 May to emission of steam and ash plumes (usually gray to dark gray) reaching a maximum height of 900 m. Ash fell on Antigua on 29 May, but clouds limited observation until evening. During the night of 29-30 May a red glow was seen over the summit, accompanied by occasional incandescent eruptions. Glowing avalanches flowed down canyons on the NE and SE flanks. After sunrise on the 30th, black ash could be seen discoloring a cloud bank 1,000 m above the summit before visibility was totally obscured at midmorning. Activity the next day was weak and no incandescence was observed.

The following information is from Samuel Bonis, David Harlow, and Keith Priestly (see 3:7 for 1-14 June observations). Fuego's eruption intensified on 15 June. Two viscous flows were extruded from the summit area and traveled slowly down canyons on the E and SE flanks, accompanied by vigorous ash ejection. This activity continued the next day, accompanied by almost constant rumbling. The ash cloud rose an estimated 3 km on the 16th and was seen by airline pilots from as far away as the Mexican border, about 170 km NW. At Yepocapa, 1-2 mm of ash fell in about 1.5 hours. By 17 June, lava extrusions had ended, and explosive activity was confined to weak ash emission, which was continuing on 19 June.

Lava flows, hot avalanches, and explosions in June; activity declines in July

Between 1 and 6 June, activity was confined to weak steam and ash emission from the summit crater and vapor emission from a small subsidiary vent near the summit. During the late afternoon of 7 June, steam and ash clouds rose 1,100 m, and after sunset loud rumbling was heard for several hours. Activity was very weak on 8 June and clouds obscured the volcano on the 9th.

Several incandescent avalanches were observed flowing down a canyon on Fuego's E flank before dawn 10 June, and that evening more incandescent material was seen in the same canyon, as much as 725 m below the summit. Similar activity was observed 11-12 June, but during the morning of the 13th, only weak steaming was visible.

A lava flow moved slowly down the E flank canyon after sunset on the 13th, to about 550 m below the summit. The volcano was obscured by clouds on the 14th and much of the 15th, but lava was visible during the evening of the 15th. Activity intensified on 16 June. At 0700, three lava flows were moving down the E and NE flanks, and at 1100 a hot avalanche traveled several kilometers down the NE flank as ash rose 1,900 m from the summit crater. Felt earthquakes accompanied by loud rumbling occurred at 1400, followed by a 2,300-m ash cloud and hot avalanches at 1600. Throughout the evening, several streams of lava could be seen descending the E and NE flanks. Lava extrusion had ended by the next morning, but a few hot avalanches were observed.

Activity between 18 and 25 June consisted primarily of weak steam and ash emission, but some incandescence was seen above the summit on 19, 21, 24, and 25 June. A hot avalanche was observed early on 26 June accompanied by 1,200-m ash clouds. Incandescent material, possibly another lava flow, reached a level more than 1,000 m below the summit in 4 hours of evening activity. Incandescent ash rose about 800 m above the summit and loud rumbling was heard. Similar activity continued through the end of June, with frequent hot avalanches and accompanying vertical emissions rising as much as 2,200 m.

Powerful explosions were heard at 2230 on 30 June and at 0215, 0700, and 2300 on 1 July. The 3rd explosion produced a 2,200-m ash cloud; the 4th caused a strong air shock at the base of the volcano, and yellow to red ejecta including large blocks rose a short distance above the crater.

Poor weather conditions prevented observation of Fuego during much of July. The volcano was inactive during brief periods of visibility on 4 and 5 July, but incandescence was observed above the crater on the 6th and a glowing avalanche moved down the NE flank. Some incandescence was visible above the crater on 8 July. Activity was limited to weak steaming and a few ash puffs between 12 and 19 July. A hot avalanche flowed about 800 m down an E flank canyon on 21 July and ash rose about 1,000 m on the 21st and 22nd. On 23 July, the last day of observations reported here, only weak ash emission was observed.

Intermittent ash emission continued through late August, but no new lava flows were reported. The maximum observed ash cloud height was about 1,650 m, on 18 August. Summit glow and ejections of incandescent material were often visible at night.

Numerous hot avalanches moved down the NE, E, and SE flanks during the late afternoon and evening of 24 July. Small incandescent ejections were seen the next night and dark gray ash rose to 1,100 m the morning of the 26th. Activity had declined by that evening, and was characterized through the end of July by the emission of small, dense, brown to black ash puffs. Occasional jets of incandescent material from the main crater and fumarolic activity from a vent near the main crater were seen 29 July.

Activity declined further in early August. Very weak black ash emission during the morning of 1 August was succeeded by steaming that continued intermittently through the next day. Ash emission resumed 3 August and jets of incandescent ejecta were seen at night. Ash clouds rose about 800 m on 4 August; each ejection lasted 3-4 minutes followed by about 30 minutes of quiescence. Clouds obscured the volcano 5-9 August.

A series of loud rumbling sounds was heard in Antigua during the late afternoon and evening of 9 August. Another rumble was heard early 10 August, accompanying the ejection of an 1,100-m black ash cloud. Intermittent ejection of black ash continued for the next several days. Clouds rose to 1,200 m on the 12th and 1,600 m on the 13th, and a small earthquake was felt in Antigua at 2214 on 12 August. Incandescent ejecta were seen after sunset on 10, 11, 13, 14, and 15 August. A hot avalanche traveled about 600 m down the E flank on 17 August.

Immediately after a magnitude 5.4 earthquake at 0936 on 18 August, 51 km W of Fuego, ash emission became more voluminous. That evening ash clouds reached about 1,650 m above the summit. Early on 19 August, ash rose 1,100 m above the summit and a hot avalanche moved about 550 m down the SE flank late in the afternoon. Incandescent material was occasionally seen during the evenings of 19-21 August, but clouds prevented daylight observations. Activity weakened 22-23 August (the last days of observations reported here), with weak steaming and ash emission from several summit area vents.

The weak activity of 22-23 August continued on the 24th. Activity strengthened on 25 August, and between the 25th and 28th varied from emission of thin grayish clouds about 1,000 m high, to ejection of larger, more ash-saturated clouds about 1,500 m high. On 29 August, intermittent bursts of dense black ejecta were thrown slightly above the crater rim during the morning, and incandescent ejecta rising to about 550 m were seen after sunset. Weak ash emission was briefly visible through clouds the next day, then clouds and rain obscured the volcano until 2 September. That evening, incandescent material, including large blocks, was thrown to about 550 m. An avalanche of yellow-orange to red material, originating from the toe of what appeared to be a short lava flow just below the crater rim, traveled down a canyon on the E flank. After midnight, a nuée ardente traveled down the same E flank canyon to the foot of the volcano. Between 0630 and 0930 on 3 September, a cauliflower-shaped eruption cloud rose to 5,500 m above the crater and nuées ardentes flowed down the E flank canyon. Ashfall was confined to Fuego's flanks. Rumbling and felt seismicity accompanied the activity during the night of 2-3 September and the morning of the 3rd. Clouds obscured the volcano for much of 3 September, but a 2,200-m eruption cloud and a large red glow were visible above the crater in the early evening.

Activity had declined to weak steam and ash emission early on 4 September, although incandescence was seen through clouds that night. From 4 to 14 September, clouds of varying ash contents reached a maximum observed height of 1,100 m (on the 8th) but most rose only a few hundred meters and there were periods of quiescence. A small earthquake was felt for about 3 seconds in Antigua at 1305 on 7 September, and a much larger, magnitude 5.5 (mb) event, 67 km WNW of Fuego, was felt there at 1724 on 10 September, continuing for nearly 1 minute. A rounded dome or cone could be seen protruding over the top of the crater rim.

Glow was seen over the crater after sunset on 14 September and intermittent incandescent activity occurred the next night. On 16 September, voluminous dark gray ash clouds were emitted to 1,100 m and a thunderstorm generated large lightning bolts that struck Fuego's crater just before sunset. Similar ash ejection occurred on 17 September. Incandescence was seen above the crater that night, as hot avalanches traveled down a canyon on the E flank. Black and gray ash rose as much as 2,000 m on the 18th and intermittent incandescence was visible at night. Rain and clouds prevented further September observations.

Fuego's eruption declined substantially in October. The summit dome noted last month continued to grow. Fuego was steaming weakly on 23 September and a brief break in the clouds on the 24th revealed no activity. Voluminous steaming had begun by the morning of the 25th. That night, a glowing avalanche traveled about 550 m down a canyon on the E flank. After dawn on 26 September, steam rose slowly to about 1,100 m, then clouds prevented further observation. Weak steaming was seen after dawn the next day. Beginning before dawn on 28 September and continuing through the evening, nuées ardentes moved down the E flank canyon. Red glow and some small incandescent eruptions were visible at night. Heavy cloudiness prevented observations on 29 September, but brief glimpses of the volcano on 30 September and during the day on 1 October showed no explosive activity. Weak ejections of incandescent material after sunset on 1 October were separated by long periods of quiescence. After 1 October, no ash or incandescence was seen. Although the summit dome was clearly growing, other activity was confined to weak or moderate steaming from the summit crater, and occasionally from two smaller vents near the summit. The maximum steam plume height during the period was about 1,000 m. Small earthquakes were felt in Antigua at 1209 on 4 October and at about 0245 on 22 October.

After a month of dome growth and weak steaming, lava flow extrusion began in late October and was continuing in late November.

The following is from Paul Newton. Fuego's activity was limited to weak steaming from 24 October until the evening of 28 October, when a loud explosion was heard at 1930. About 30 minutes later, avalanches of glowing ash and some large blocks began to travel down Barranca Honda (figure 1), a canyon on Fuego's E flank. Hot avalanches continued through at least 1130 the next day, accompanied by weak steaming. The SE side of the summit dome appeared "distorted" from Antigua. Clouds then obscured the volcano until 1830 when a glow was visible over the summit but hot avalanches had ceased.

Only minor steaming was observed between 30 October and 4 November. The vapor column reached 700 m in height on 5 November. Incandescent avalanches resumed by the evening of 6 November, stopped by the next morning, then began again during the evening of the 7th and continued through 12 November, the last day of Newton's observations. Weak steaming and occasional emission of dark gray ejecta to a maximum observed height of 500 m accompanied the avalanches. Earthquakes were felt in Antigua at 1224 and 1312 on 30 October, and at 0030 on 31 October.

The following report, by Dennis Martin, is based on observations from the E side of Fuego 19-20 November, and from Alotenango (at Fuego's NE foot) beginning 21 November, plus conversations with local residents. "An incandescent lava flow about 300 m long extruded from a vent just E of and below the summit was flowing down Barranca Honda. Where the slope within the barranca steepens to more than 60°, the flow formed a spectacular lava cascade where incandescent lava blocks dropped hundreds of meters. Extending about 3 km further down the Barranca to elevations of about 2 km was a block avalanche fed by accumulations of incandescent blocks from above. This avalanche continually oversteepened and produced its own incandescent cascades. At night, incandescence from the block avalanche disappeared below about 3 km elevation. Because of accumulations high in Barranca Honda, a block avalanche had began to advance down an adjacent canyon (N of Barranca Honda) in mid-November. Both avalanches had reached a point about 6 km from National Route 14, where the nearest people live. Weak, sporadic lava fountaining at the summit mound and gas emission from an apparent 500-m-long N-S fissure accompanied the lava flow.

"A moderate Vulcanian eruption, similar in intensity to the 29-31 January events began at 0030 on 21 November. The eruption cloud rose more than 2 km and was blown WSW and W. Incandescent blocks were thrown to a height of a few hundred meters. An apparent ash flow descended the Barranca Honda at 0430. The loudest of nearly continuous audible explosions heard at Antigua occurred at 0600, but by 0900 the eruption was clearly decreasing in intensity and continued to do so for the rest of the day. By the evening of 22 November, the Vulcanian activity had declined to 1-2-minute explosions at about 2-hour intervals. The lava flow activity of the previous weeks continued during the Vulcanian eruption."

Information for the period 23 November through 5 December is from Don Willever and Paulino Alquijay, compiled by Paul Newton. Observations from 6 through 18 December are by Paul Newton. Clouds frequently obscured the volcano, permitting only brief views of the summit area on many days.

After the moderate Vulcanian eruption of 21 November, activity had declined to occasional explosions and intermittent ejection of small amounts of incandescent material by the night of 22 November. No activity was visible when clouds briefly dissipated on 23 November. Between 24 November and the evening of 2 December, steam and ash clouds, usually white or gray but occasionally black, were ejected intermittently from the main crater, and steam was emitted from the N-S-trending fissure extending northwards from the summit. The steam and ash clouds usually rose only a few hundred meters, but an 1,100-m column was seen early on 28 November. A weak glow could be seen over the crater at night, but no lava fountaining or flows were reported.

Lava fountaining from the summit crater was observed after sunset on 2 December. The next night, incandescent material was visible in Barranca Honda, the principal lava flow channel on Fuego's E flank. Intermittent steam and ash emission, similar to the 24 November-2 December activity, was reported on 4-5 December. Clouds prevented observations on the 6th, but lava was seen in Barranca Honda on the morning of 7 December. Only weak steaming occurred on 8 December. Cloudiness obscured the volcano until after sunset on the 10th, when incandescent material rose a short distance above the summit. Low but voluminous black clouds were ejected the next day, then weather clouds prevented observations on 12 December. Activity was weak during the morning of the 13th, but frequent bursts of incandescent ejecta were thrown more than 500 m above the crater after sunset. Ejection of incandescent material was visible each night through 18 December, the last day of observations. Dense gray ash clouds rose about 700 m above the summit. Block avalanches, or rising dust produced by them, were seen in Barranca Honda on 15 and 16 December.

The following is from a report by Dennis Martin. "By 16 December, the summit mound seemed to have grown markedly, perhaps more than 100 m in height since 21 November. Between 11 and 16 December, ash-laden clouds were ejected at intervals of a few seconds to a few minutes, to a maximum height of approximately 1 km. Most clouds rose only a few hundred meters and were blown away by predominantly westerly winds. The duration of explosive intervals varied from 1 second to 2 minutes. At night, fountains of molten lava thrusting up to a maximum of 750 m could be seen within the ash-laden gray clouds. These incandescent blocks cascaded in a spectacular display from 100 to 1,000 m down the flank. However, the incandescent lava flow and resulting block avalanche down Barranca Honda were no longer visible. A walk up the Barranca Honda on 13 December confirmed that the block avalanche had stopped at approximately 2,600 m elevation. The new lava is a vesicular, olivine-bearing basalt like previous Fuego magmas."

Sporadic ejection of ash clouds, sometimes accompanied by incandescent material, continued through early January. Lava flows and block avalanches moved down the E flank 6-8 January, then a pattern of intermittent ash emission and occasional fountaining resumed, continuing through 21 January. Fuego's summit was only briefly visible through clouds on many days of the 19 December-21 January observation period, but was totally obscured only on 3-4 and 12 January.

A thin ash column rose more than 1,300 m during the late afternoon of 19 December and a small ash flow moved down Barranca Honda the next morning. Low incandescent ejections were visible during the night of 21-22 December, but ash rose only about 0.5 km the next day. On the 23rd, voluminous ash clouds were ejected to about 1 km above the summit and there was a slight ashfall in Antigua. That night incandescent ejecta was again visible, and ash and small blocks flowed about 500 m down Barranca Honda. Ash clouds as high as 1,600 m were emitted on 24 December, but activity declined to minor steaming between the 25th and 31st. Ejection of incandescent material after sunset on 31 December and 1 January was succeeded by weak steaming through 5 January.

Before dawn on 6 January, lava began to flow down Fuego's E flank, dividing into separate streams that moved down Barranca Honda and several other canyons with a rolling, tumbling motion (see the description of lava cascades at Fuego in 3:11). Large blocks fell away from the main body of the flow, and a persistent brighter red area could be seen about 200 m below its source. On the 7th, a dense dust cloud rose from Barranca Honda and remained above it through evening, as lava continued to flow down the E flank. At 0400 on 8 January, a loud explosion was heard in Antigua and bursts of incandescent ejecta were thrown about 0.5 km above the crater. After dawn, ash clouds could be seen rising 2 km. Some of the ash was ejected from the base of the summit mound at an angle of about 30° from the vertical. Nuées ardentes flowed down the E flank. By late morning, the height of the ash columns was decreasing and ash emission had ended by late afternoon.

Several streams of lava continued to flow down the E flank through the 8th and block avalanching was prominent that night. However, only weak steaming was observed from 9 January until the night of 14 January, when small bursts of incandescent material were ejected from the summit crater and red glow in Barranca Honda was barely visible through dense haze. Weak ash emission on the 15th was succeeded by low but more voluminous ash clouds on the 16th, accompanied by a brown dust cloud that was present over the entire visible length of Barranca Honda. That evening, low but dense black clouds dropped ash onto the NW flank and brilliant bursts of lava and blocks were ejected nearly vertically from the foot of the summit mound to a height of about 0.3 km. A block avalanche descended Barranca Honda, then clouds prevented further observations. Similar but slightly stronger activity was seen on 17 January. Only weak steaming was visible during the day on the 18th, but at night bursts of lava fed block avalanches that traveled almost 1 km down Barranca Honda. Intermittent dark gray to black ash columns rose more than 1,100 m on 19 January. A light fall of fine ash on Antigua obscured the volcano from view on 20 January. The next morning, low lava fountaining was visible before dawn. Ash clouds rose more than 2 km by the evening of the 21st, accompanied by moderate ash emission from the base of the summit mound, at an angle of 40° from the vertical.

One large and several small earthquakes were felt in Antigua during the observation period. The largest was a magnitude 5.5 event centered 67 km SE of Fuego on 12 January.

After considerable lava extrusion and ash emission in early to mid-January, Fuego's activity was confined to weak steaming between 24 January and 7 February. Clouds obscured the volcano 22-23 January and from 8 February until sunset the next day.

Renewed visibility late on 9 February revealed red to bright orange-yellow block lava flowing down Barranca Honda, a canyon on the E flank. Large blocks bouncing from wall to wall of the canyon could be seen from Antigua. The next morning, dense black ash clouds were ejected, obscuring the summit area, and white vapor clouds reached a height of 2.5-3 km above the summit. By nightfall, black ash emitted from two vents formed a thin column about 1 km high and white vapor moved upwards about an additional 1.3 km. Bursts of incandescent material were thrown more than 200 m above these 2 vents. A large amount of block lava flowed down Barranca Honda, but blocks did not bounce out of the flow as they had the previous night. Lava also flowed into a second canyon N of Barranca Honda. Later in the evening, less lava was moving down Barranca Honda, but large numbers of incandescent blocks were thrown onto the N shoulder, then disappeared from view down the W flank (not visible from Antigua).

Clouds prevented night observations 11-18 February, and no lava was seen in Barranca Honda in the daytime during this period. However, ash emission continued, reaching a maximum observed height of 1.5 km and frequently rising about 1 km. Eruption clouds decreased in height and their ash contents declined 16-17 February, and no ash rose above low summit-area weather clouds on the 18th.

About midday on 19 February, block lava could again be seen flowing down Barranca Honda, and low clouds of black ash were ejected from the vents. After dark, several streams of lava were visible, flowing down Barranca Honda, a canyon to the N, and an open area on the NE flank. Glowing blocks tumbled away from the flows. On 20 February, the last day of observations reported here, lava extrusion persisted and dense black ash clouds rose about 0.5 km.

No earthquakes were felt in Antigua during the observation period, but persons nearer the volcano felt some shocks and heard numerous rumblings.

The extrusion of block lava observed 19-20 February was no longer visible by sunrise on the 21st. Dark gray to black clouds were ejected sporadically that morning, rising as much as 500 m, but ash contents declined in the afternoon, and by 1930 no activity was visible. Only intermittent emission of vapor, sometimes containing a little ash, occurred 22-24 February, with columns reaching a maximum estimated height of slightly more than 1,000 m. Activity declined further, to low but voluminous steaming from vents on the E and SW sides of the summit cinder cone, on 25 February. Mild steaming followed for two days. Slumping on the SE side of the summit cone was first observed on the 27th. After clouds obscured the volcano on 28 February, sporadic ejection of gray steam and ash columns could be seen on 1 March. The columns rose as much as 1,400 m on the lst and more than 2,000 m on the 3rd. The summit showed no activity early on 4 March, after which a period of cloudiness prevented observations until the 9th.

Activity 9-13 March ranged from periods of very mild steaming to emission of ash clouds that rose to a maximum observed height of 1,500 m on the 10th. Significant quantities of ash could be seen falling on Fuego's N and E flanks on 13 March. The slumped area on the summit cone had become a clearly-defined, wedge-shaped fissure by mid-March, extending from near the summit to somewhat less than halfway down the SE side of the cone.

Extrusion of block lava resumed on 17 March, after three days of weak steaming. The flow first became clearly visible after sunset, but probably began at or before daybreak, appearing to originate from the base of the summit cone fissure. Lava moved about 0.5 km down Barranca Honda. Many large blocks tumbled down the canyon. At 1915 on 18 March, an explosion ejected incandescent tephra, including large blocks, to a height of about 500 m. Clouds obscured the volcano on 19, 20, and most of 21 March; continuing lava extrusion was briefly visible on the 21st. Explosive activity on 22 March, the last day of observations reported here, produced ash clouds that rose about 2,500 m, accompanied by spectacular lightning. Fine ash fell on Antigua.

Fuego's pattern of frequent ash emission and occasional extrusion of block lava continued through late April. Cloudiness obscured the volcano frequently during this period, as Guatemala's rainy season approached.

The strong explosive activity observed on 22 March had declined somewhat by the following morning, but ash emission remained voluminous for the next several days. Dense black ash rose as much as 0.7 km and vapor reached a height of 1.3 km. Ash fell on Antigua on 23 and 25 March.

Activity intensified on 29 March. During the early morning, a black eruption column was ejected to more than 1 km over the summit. By late afternoon (when cloud conditions again permitted observations) the height of the eruption column had decreased but heavy ashfall was occurring on the flanks. Sporadic ejection of incandescent tephra was visible after sunset, and a glowing avalanche traveled down the E flank. Block lava extrusion began the next day, probably by morning, when dust could be seen rising from Barranca Honda. By evening, slow-moving lava had flowed more than 0.5 km down the canyon, and some large blocks had tumbled from its upper end. Small amounts of incandescent tephra could be seen emerging from a vent W of the summit cone.

Clouds obscured the volcano for most of the period 31 March-5 April. A dark gray eruption column, about 0.5 km high, was briefly visible on 31 March, and mild to moderate steam emission could sometimes be seen in the mornings during the cloudy period. On 6 April, a glowing avalanche descended Barranca Honda, and steam and ash were sporadically ejected from the summit. Stronger ash emission occurred the next day, causing heavy ashfall near the summit. Vapor clouds rose higher than the ash, to 1.1-1.7 km. The fissure on the summit cone had been substantially filled by ash.

Small bursts of incandescent tephra, separated by 5-18-minute periods of quiescence, were seen during the evening of 7 April. Activity was limited to mild steaming during the day on the 8th, but low, sporadic ejection of incandescent tephra could be seen after sunset. A 4-5-second, very low-pitched rumble was heard in Antigua just before midnight. Ash fell on Antigua during each of the next 3 days, while the volcano was hidden by clouds. Between 12 and 14 April, gray ash and vapor were intermittently ejected, rising as much as 750 m. Ash content of the eruption clouds increased on 15 April. A new fissure that had formed in the top of the summit cone was the source of low emission of black ash.

At 0820 on 16 April, deep rumbling was followed by an explosion that produced a 2.1-km-high ash cloud. Poor weather prevented further observations on the 16th, but by the next morning, maximum ash cloud heights had declined to about 0.5 km. Some incandescent tephra was visible, falling a few hundred meters from the summit cone.

Although clouds obscured the volcano from 18-20 April, ashfalls in Antigua on each of these 3 days indicated continuing activity. When visible through clouds 21-23 April, ash emission was moderate, rising about 0.5-1 km. Better visibility on 24 April revealed ash ejection from the fissure at the top of the summit cone; ash rose about 0.5 km and white vapor as much as 2 km. Ash again fell in Antigua on 23-24 April, the last days of observations reported here.

Activity observed at Fuego during the 26 April-24 May reporting period was limited to intermittent and usually weak ash ejection. All of the ash appeared to originate from the summit cone fissure, but Newton suggests that significant quantities may also be ejected from vents on the W side of the summit area, not visible from his vantage point. Clouds prevented any observations on 25, 27, and 28 April and 2, 5, and 19-23 May, as well as limiting visibility to brief glimpses on many other days.

From 26 April through 9 May, Fuego's eruption column was gray to black, usually rising 0.5 km or less. Ash ejection was often intermittent, as on 3 May when low but voluminous ash clouds were emitted for 4- to 7-minute periods, separated by 5-8 minutes of quiescence. Windless conditions allowed the ash column to rise an estimated 1.4 km on 6 May and 1.6 km on 9 May. Fine ash fell on Antigua, 17 km NE of Fuego, on 1, 7, and 8 May. A hot avalanche appeared to descend about 0.5 km down an E flank canyon on 30 April.

A small earthquake, lasting less than 2 seconds, was felt in Antigua at 1700 on 9 May. Rumbles were heard there the next morning, at 0300, 0400, 0600, and 0630, the last of which was quite loud. After dawn, thick and voluminous ash clouds were ejected to about 0.5 km above the crater. By midmorning the plume was white, rising a maximum of 1.4 km in still air. That night, the only incandescent material observed during the reporting period was ejected to a short distance above the summit.

Activity similar to that of 26 April-9 May resumed on 11 May. Intermittent bursts of black ejecta rose about 0.5 km, accompanied by steady steaming. Larger ash clouds were ejected on the 15th (to 1.6 km) and 16th (more than 2 km), then activity declined on 17 May to mild steaming and a single burst of gray ash to about 0.5 km above the crater. During the 2 hours of visibility the next day, no activity was observed. What appeared to be dense white gas was twice seen flowing down an E flank canyon during this period, on 14 and 17 May.

Clouds obscured the volcano 19-23 May. A mild, 4-second earthquake was felt in Antigua at 0300 on the 20th and a single sharp shock at 2315 on the 21st. Residents of Alotenango, at the base of Fuego, had reported numerous rumblings and earthquakes during a 15-day period prior to 17 May.

Although fine ash fell on Antigua on 22 and 23 May, only a very small plume, rising less than 0.3 km, was seen on 24 May, the last day of observations reported here.

Activity at Fuego remained intermittent and relatively weak during most of the 25 May-27 June reporting period, although vigorous ejection of incandescent tephra occurred on 20 June. Rainy season clouds often made observation of the volcano impossible, particularly in early June.

During periods of visibility between 25 and 30 May, Fuego's activity was usually confined to mild steaming from the summit. However, voluminous black ejecta rose about 3/4 km early on 25 May and about 0.5 km in the late afternoon of 30 May, the latter followed by a light ashfall on Antigua. On 2 June at 1615, a brown tephra cloud was ejected at high velocity to 2.5-3 km above the summit. The volcano was briefly visible late the next afternoon, but no activity was taking place.

Except for a 30-minute period on 7 June (when it was inactive) Fuego was obscured by clouds 4-11 June. Weak vapor emission was glimpsed through clouds on 12, 13, and 15 June. Ash ejection was seen twice between the 16th and 19th, to 0.3 km height early 16 June and to about 0.5 km 24 hours later, but the volcano was otherwise inactive.

On 20 June, weak emission of light brown ash to 400 m height was followed at 0930 by ejection of incandescent tephra to more than 0.8 km above the summit. Large yellow, orange, and red blocks fell on the flanks before clouds prevented further observations at 1030. Intermittent voluminous ash emission could be seen for the next four days, some originating from a vent W of the summit. Maximum cloud heights were about 0.7 km. When the volcano was next (briefly) visible, on 27 June, activity had declined to occasional steaming.

Activity at Fuego increased during July. Voluminous ash clouds frequently rose more than 1 km above the summit, and incandescent tephra was seen on several occasions, but no new lava flows were reported.

During the afternoon of 29 June, an explosion projected a black eruption cloud to about 2.5 km height, but activity quickly declined to intermittent gray steam and ash emission. When the volcano was next visible, on 3 July, occasional low-velocity bursts of brown to black tephra rose about 0.7 km. Tephra rose only about 0.5 km the next day, but incandescent material was ejected a short distance above the summit that night. After Fuego was obscured by 2 days of clouds, ash emission was voluminous and steady early on 7 July, rising to about 1.5 km. Shortly after sunset, incandescent tephra rose about 0.3 km, and large blocks fell on the flank. This activity intensified 45 minutes later, some tephra reaching an estimated 1.8 km above the summit, then subsided after about 10 minutes. The next day a brief explosion produced a 2-km-high voluminous gray-black cloud, but otherwise only weak steaming was visible. During the early evening three loud explosions were heard from Antigua but the volcano could not be seen through clouds. Several explosions, similar to the one observed on 8 July, took place on the 9th, with clouds reaching maximum heights of 1.5 km. Ash fell on the flanks of Fuego and adjacent Acatenango. The S end of the summit fissure could be seen to have widened.

Activity ceased the evening of 9 July, and only weak steam emission was seen 10-13 July. A single explosion produced a 0.75-km-high gray cloud on the 14th. Clouds obscured the volcano the next day. On 16 July, weak steaming during the day was succeeded by 15 minutes of thick intermittent bursts of black ejecta, rising about 0.5 km. Two small incandescent ejections were seen after nightfall.

Clouds prevented observations 17-18 July. Brown eruption columns were seen above the clouds on three occasions 19 July, rising an estimated 1.5-2 km. After another cloudy day on the 20th, a 0.6-km black ash column was seen in a brief clear period on the 21st. On 22 July, sporadic bursts of brown tephra produced dense clouds that rose 1-2 km. Eruption cloud densities declined 23-24 July, and reached heights of 1 km or less.

The intensity and frequency of ash emission at Fuego began to decline in late July. By mid-August only weak steam emission was visible, a condition that continued through 21 August.

On 25 July, four small explosions in a 45-minute period produced dark gray ash clouds that rose less than 0.6 km, after 1 hour of inactivity earlier that morning. A similar pattern of activity was observed on 26 and 27 July, but ash clouds were more voluminous, and reached 0.8 km on the 27th. Only steaming took place on 28 July until late afternoon, when 3-4-minute bursts of gray ejecta, rising to more than 1 km above the summit, occurred at intervals of 10-30 minutes. The next day, long periods of quiescence separated voluminous, but ash-poor emissions lasting 2-4 minutes each. The volcano was inactive on 30 July and only weakly active the following morning, but at 1330 on 31 July, the largest explosion of the reporting period took place, producing a cloud that rapidly rose to more than 2 km. Weak steam and ash emission followed this explosion, and similar activity was visible on 2 and 3 August (after a cloudy day on 1 August).

From 4-7 August, steam and ash emission was very weak, and by 8 August was interspersed with periods of complete inactivity. No activity was occurring during 1-hour breaks in cloud cover early on 9 and 10 August. Clouds obscured the volcano 11-12 August, but clear visibility 13-15 August revealed no activity. Fumarolic emission from a subsidiary vent near the summit resumed on 16 August and was continuing on 21 August, the last day of observations reported here.

From late August through late September the summit was usually obscured by clouds. When the volcano was visible (26-29 August, 4-7 and 11-13 September), only steaming took place, from some or all of several vents high on the E and ENE flanks. Two fissures, of approximately equal depth, emitted steam S of and slightly below the top of the summit cone. Although winds for the past 2 months have frequently blown from Fuego toward Antigua, no ashfalls have occurred there during that time, in contrast to earlier, more active periods.

Unusually heavy rains have caused landslides and widespread flooding throughout Guatemala, resulting in many deaths, major crop losses, and closures of main road and rail transportation routes. Secondary mudflows formed from tephra on Fuego's flanks have been particularly destructive, as far downstream as the coastal plain.

Activity was again limited to steaming from the summit crater and several other vents high on the flanks between late September and late October. Steaming was occasionally quite voluminous early in the reporting period, but had weakened considerably and was interspersed with periods of inactivity by late October. A clear view of the summit on 18 October revealed that a new crater had formed a short distance from two fissures seen the previous month.

Paul Newton and Paulino Alquijay have continued to monitor Fuego from Antigua since last October. Intermittent vapor emission from the summit and several other vents high on the flanks continued through January. Vapor occasionally rose more than 1 km above the summit, but activity was often weak and there were periods of as much as four days when no vapor emission was visible from Antigua.

The following report from William I. Rose, Jr., is based on air and ground observations between 22 January and 10 February. "Fuego was in a state of continous gas emission, mainly from vents around the edges of the summit crater. The plume varied considerably in intensity, but on its most impressive days it extended many tens of kilometers. The intense fumarolic activity at and around Fuego's summit has produced a broad white and yellow zone of encrustations above about 3,500 m elevation. The crater itself was 35 m in diameter, symmetrical, and about 20 m deep."

On 16, 17, and 18 February geologists visited the summits of Fuego and Acatenango Volcanoes. Comparisons of photographs of Fuego taken on this expedition to ones taken by W.I. Rose, Jr., in February 1980 showed no striking physical changes in the summit region. The main areas of gas emission, on the N and the SE sides of the main crater, were the same as in 1980. The SE area is a spatter vent from Fuego's last eruption in 1977-79. During the group's visit, gas was being emitted at a moderate, steady rate, as in early 1980. On 21 February, however, the group observed that there was a clear pulsation in the rate of emission, with a period of about 2 minutes. A light wind on the 21st allowed the gas plume to rise nearly vertically about 400 m above the crater. Around the crater rim there were only a few fumaroles in contrast to many in early 1980. New fumaroles had appeared around and atop an older irregular domal protrusion on the W flank of the summit.

In early January, incandescent tephra ejection was visible from Antigua, 18 km NE. Some tremor may have been associated with the January activity. Only block ejection and increased fumarolic activity were reported in early February. Fuego's last reported eruption began in September 1977 and continued through mid-l979. Moderate explosions fed tephra columns and small pyroclastic flows; a summit lava dome formed and lava flowed down the upper flanks.

About 78 microearthquakes were recorded at Fuego station (FG3), 5 km [SE] of the summit, between 1300 and 1500 on 8 June. Residents of the area reported that they did not feel any earthquakes. An electronic tiltmeter at the seismic station measured 8 microradians of deformation. On 10 June, a white vapor column was observed emerging from the crater.

By May, visible activity was limited to a weak white plume from the summit crater. A seismic station (FG3), 5 km SE of the summit at 1,500 m altitude, registered 30 microearthquakes with S-P <= 2.0 seconds during May and 40 in June. On 8 June, residents of Guatemala City observed a white vapor column extending hundreds of meters above the summit. This coincided with an apparent earthquake swarm and a 10 microradian change on the electric tiltmeter installed in March at the same location as the seismic station (12:05). During the following days, INSIVUMEH personnel installed portable seismic stations 10 km E and W of the summit (at Alotenango and San Pedro Yepocapa). These did not register any seismicity. INSIVUMEH geologists suggested that heavy rains on 8 June may have been responsible for the observed activity.

Gas emission from the crater and nearby microearthquakes continued through July. Seismic station FG3 registered 50 microearthquakes with S-P <= 2.0 seconds. The tiltmeter, at the same site, did not show abnormal variation. A small fumarole was also active about 100 m below the crater on the E flank.

Strong gas plume extends several tens of kilometers from the summit crater

Geologists observed a vigorous and persistent gas plume that extended several tens of kilometers W from Fuego's summit crater during work at neighboring Acatenango on 6 January between 0900 and 1400. Frequent rock avalanches occurred in the upper parts of Barranca Honda, a steep E flank canyon.

Overflights of Fuego were made on 15 and 16 February by volcanologists from INSIVUMEH and Michigan Tech. The following is from their report.

"Continuous gas emission was observed, with no evidence of any magma at the surface. The geometry of the summit crater and its surroundings (which influences the paths of pyroclastic flows during eruptive activity) was unchanged since 1980. COSPEC measurements of SO2 emission rates were made from the air, yielding 265 ± 33 t/d on 15 February and 120 ± 30 t/d on 16 February (3 and 8 determinations respectively). These rates are very similar to the 100 t/d measured in February 1980 and much less than the rates measured in February 1978 (660-1,700 t/d) when Fuego was actively erupting (Stoiber et al., 1983; reference under Santiaguito)."

During an aerial survey on 10 February, no changes in crater morphology were evident since the previous overflight a year earlier (15:03). The plume remained prominent, and SO2 emission measured by COSPEC was 190 ± 21 t/d.

An apparent harmonic tremor episode was recorded in mid-April, prompting the placement of several additional portable seismometers on the volcano in early May. Since then, several tectonic earthquakes have been recorded, but no harmonic tremor. Fumarolic activity continued in the summit crater.

During 12-19 November a white-to-gray column was observed rising 70-200 m above the crater; winds then dispersed it to the S over the volcano's flanks. On 20 November the column rose to 500 m and drifted E; the following day the column's height was 200 m and oriented SW. From 25 November to 12 December the column was again at 50-200 m height and blown toward the S and SW. During this observation period the Fuego-Acatenango seismic network recorded a few earthquakes up to M 1.

Eruption on 21 May dropped up to 40 cm of ash on local population; small lava flow

Reports from INSIVUMEH described an eruption during late May 1999, the first from Fuego since 1987. At 1000 on 21 May observers noted that small quantities of ash fell on the cities of Villa Nueva, Barbarena, Cuilapa, Jutiapa, and Chiquimula. At 1800 on 21 May an eruption sent ash to the S, SE, and SW. The regional ashfall affected areas including the peak ~4 km N (Yepocapa), the cities of Alotenango, Escuintla, Santa Lucia, Cotzumalguapa, Palin, Amatitlán, and the slopes of Pacaya volcano. Ash thicknesses at proximal sites were 10-40 cm. At 2100 the activity diminished, but continued with moderate 3-minute explosions. The Aeronautica Civil recommended that planes should not go any closer than 40 km from the volcano. At 2200 a lava flow ~200 m long was seen on the W side of the Barranca Honda drainage. By this time, the atmospheric ash had settled, and the Aeronautica Civil recommended not flying closer than 15 km from the volcano.

INSIVUMEH reported that NOAA detected ash over much of Guatemala to 14-15 km altitudes. It was not possible to see the activity in the crater, and the meteorological conditions for the next 24 hours consisted of electrical thunderstorms with rain in the afternoon and evening. At 0530 the seismic station "FG" located in the FICA La Reunion, 3.5 km E of the crater, registered movement beneath the volcano. Every hour for three hours, explosions sent gases and moderate ash to heights of 600-800 m.

Volcán Fuego erupted during late May 1999 (BGVN 24:04) for the first time since 1987. From 21 May through 1 September, Fuego generated moderate Strombolian eruptions. The interval between eruptive pulses was frequently 5-10 minutes; in some cases ash columns rose as high as 800 m above the summit. Ash fell up to 15 km away. At night, incandescent displays rose ~250-300 m above the crater rim. Fragmental lava ejected from the vent constructed a ~25-m-tall spatter cone that provided source material for hot rock avalanches, some with runout distances of several kilometers. Although seismicity remained weak, local residents heard very strong rumbling.

Prior to 15 July the activity hazard status of the volcano was Orange. This was downgraded to Yellow on 15 July only to be increased to Orange again on 19 July as of result a lava extrusion and frequent small ash eruptions starting around 1600 and continuing throughout the day. Small ash emissions occurred on 20-21 July. INSIVUMEH reported that 13 explosions occurred between 2300 on 20 July and 0300 on the 21st, sending some tephra up to 700 m above the summit. The hazard status was raised to Orange and pilots reported ash to altitudes of 5,500 m W of Guatemala City. For the next seven days, the volcano remained unsettled; NOAA reported that near-infrared satellite images displayed an occasional hot spot. Small ash eruptions began again on 28 July with ash clouds again attaining altitudes of 5,500 m. By that evening, eruptions were comprised mainly of steam and the status was reduced to Yellow, although INSIVUMEH advised that the volcano had the potential for an explosive eruption with little or no warning. This situation persisted with occasional ash emissions and satellite observations of hot spots until 9 August. Activity then decreased and no explosive eruptions were detected though the evening of 11 August. As of 2 September, no additional reports regarding Fuego had been issued by NOAA's Washington Volcanic Ash Advisory Center.

Fuego resumed eruptive activity on 21 May 1999 (BGVN 24:04). No reports are currently available to describe August through 27 December activity.

On 28-29 December observers noted weak, moderate, and some strong explosions that emitted gray ash 100-800 m S and SW of the vent. By the evening of 28 December it was possible to observe incandescent material over the crater. The rising ash formed a black column to 300-500 m altitude, blowing S. Until 1040, seismic data revealed 22 explosions, many of moderate amplitude.

Ash expulsions continued with associated earthquakes until 0915 the following day. Later in the reporting interval, the eruptive and associated seismic activity decreased with the exception of ~35 minutes on 28 December, when a black column of ash (blowing SW) continued to escape. Consistent explosions gave off gray ash in weak-to-moderate plumes; these reached up to ~900 m over the crater. Wind carried portions of the ash plume to the E, S, and SW. When strong, the explosions were audible in nearby villages such as El Parcelamiento Morelia and Aldea Panimanche. Volcano watchers chiefly saw explosions at night, when incandescent material rose over the crater.

Between 19 and 27 January, Fuego emitted ash plumes at frequencies which varied from less than 1 per hour to over 12 per hour. During 19 January, Fuego erupted at-least 28 times sending ash clouds to a height of ~ 600 m. These rates are higher than Fuego's typical eruption rate). Again on 24 and 25 January, small (~ 600 m high) ash clouds rose from the summit crater at a similar rate. On 26 and 27 January, when clouds did not obscure the summit, eruption rates were rather low.

Hot spots were apparent on GOES images (http://hotspot.higp.hawaii.edu/) throughout January while analysis of a Landsat 7 Enhanced Thematic Mapper scene acquired at 1030 on the morning of 23 January showed an intense thermal anomaly focused at Fuego's summit, a point source 120-150 m in diameter.

The recent activity resembles that observed in the February 1978 - May 1979 period, suggesting an open vent (Smithsonian Institution/SEAN, 1989).

More recently, on 12 February 2000, Steve and Donna O'Meara counted over 19 eruptions during periods when the volcano was visible. The volcano sent out ash puffs and moderately strong columns every 5 to 15 minutes. They reported further that they saw additional eruptions on 17 and 18 February before they departed the country.

Seismic activity during April and December, eruption in September 2000

Ash venting began at Fuego on 5 April 2000, followed by increased ash emissions and strong seismic signals during 7 and 8 April, according to the Guatemala Volcano Observatory and the Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hidrologia (INSIVUMEH) of Guatemala. On 8 April at 0215 a hot spot was visible in multi-spectral imagery. More hot spots were occasionally noted but there were no further reports of ash.

A news article from La Hora reported that a column of ash reached 1 km on 29 August 2000. According to the Guatemala Volcano Observatory, an eruption beginning on 6 September emitted an ash-and-steam plume that reached ~800 m. On 21 September a large amount of ash was emitted, blanketing nearby communities. Authorities considered evacuating residents and issued an Orange Alert for the area near the volcano.

Satellite imagery on 7 December showed an ash plume to the SW of the summit, extending 39 km and 11 km wide. According to ground observations the ash was centered at ~4.9 km elevation. INSIVUMEH reported that the volcano was producing loud rumbling sounds and a more significant eruption was likely. On 9 December 2000 satellite imagery confirmed a small eruption at about 1645. The eruption sent an ash cloud to ~4.5 km altitude, near the summit level. The ash cloud was initially dense, about 8 km wide, and drifted W and NW. By 2345, the cloud had dissipated and was no longer visible on satellite imagery. Occasional strong hot spots were visible on GOES-8 multi-spectral imagery throughout the day. That evening, volcanologists in Guatemala indicated that the volcano had become increasingly unstable with several explosions occurring within a few hours. Since then, no major activity has occurred.

At least two commercial aircraft flew through airborne ash near the Guatemala City airport on 21 May 1999. An eruption from Fuego that day was the first at that volcano since 1987 (BGVN 24:04). Although the aviator's reports attributed the ash from this encounter to Fuego, their aircraft intersected multiple ash plumes in widely different locations, and thus they may also have crossed plumes from Pacaya. The most likely plume near the southern approach to the airport (La Aurora, ~23 km N of Pacaya; ~40 km NE of Fuego) is from the almost constantly active Pacaya. In contrast, Fuego lies 32 km W of Pacaya and was the likely source of a plume intersected later during the flight, at higher altitude, and for much longer duration.

During the encounters the ~100 or more people on board the two aircraft, and many more on the ground, were at risk. Both encounters seriously damaged the aircraft but ended in safe landings without reported injuries. Volcanic ash can cause jet-engine failure, which creates a hazard not only to passengers, but to people on the ground as well. The risk in this situation was amplified by the airport's proximity to urban Guatemala City (population, >1.1 million).

This example leads to two conclusions discussed further below. First, ash avoidance methodology needs further refinement. Second, there exists an apparent bias towards under-reporting of aircraft-ash encounters, which could short-change their cost to air carriers, their perceived risk, and their funding allocation.

The original report of an aircraft-ash encounter was brought to our attention by Captain Edward Miller of the Air Line Pilots Association and provided on the condition that the air carrier remain anonymous. Bulletin editors also wish to acknowledge conversations with several additional anonymous contacts (commercial pilots). This case occurred in Guatemala; however, analogous situations exist at many airports adjacent to volcanoes. Modest eruptions from nearby volcanoes may be uncertain or difficult to see; they may be hard to detect or characterize; yet they still may yield mobile ash plumes carried by complex local winds to confront air traffic (Salinas, 2001; Hefter, 1998; Casadevall, 1994).

Although in most Bulletin reports we favor the use of local time to emphasize the reference frame of people on the scene, most of the source material (satellite and aviation) for this report refer to UTC (Coordinated Universal Time). UTC is the time on the Greenwich meridian (longitude zero), formerly GMT, a term which has fallen out of use. Accordingly, there are cases in this report that lack conversion to local time. Local time in Guatemala is 6 hours behind UTC.

Activity at Fuego and Pacaya. Fuego erupted on 21 May 1999 sending ash to the S, SE, and SW and ultimately dropping up to 40 cm of ash on local settlements (BGVN 24:04). The eruption occurred at 1800 local time (in terms of UTC, at 0000 the next day). Three hours later the eruption decreased and the Aeronautica Civil recommended that planes go no closer to Fuego than 40 km. One hour after that (at 2200 local, 0400 UTC), the atmospheric ash had settled, and Aeronautica Civil recommended flying no closer to Fuego than 15 km.

Bulletin reports for Pacaya in mid-1999 suggested relative calm, in harmony with the observation that it had chiefly been fuming. However, Pacaya is well-known for Strombolian outbursts. It lies directly in-line and only 23 km S of the N10°E-oriented airstrip. As is common for commercial aircraft there, the approaches described below passed very close to Pacaya. Pacaya typically has lower and smaller eruptions than Fuego, but because it lies so close to the southern approach to the airport, Pacaya's ash plumes easily enter the path of landing aircraft. The situation was particularly complex during this eruption because Fuego's ash was reported on cities that lie below the flight path as well as on the Pacaya's flanks.

Pilot's report of aircraft-ash encounter. What follows was taken from one flight crew's description of events and from later reports and dialog on the topic. In order to preserve the confidentiality of the airlines, the precise times of events on 21 May 1999 have been omitted. Pilots reported clear visibility and light wind, with both the capital and the airport in sight. They maneuvered the aircraft for a final approach from the S. Pilots were advised by air traffic control about erupted particulate ("volcanic sand") about 24 km (15 miles) SE of the airport, well away from their projected path to Runway 01. In addition, based on winds they detected as they neared the airport, the pilots concluded that the erupted particulate to the SE was downwind from their projected flight path to the airport. (In retrospect, this conclusion appears tenuous considering the possibility of either a fresh injection of ash from Fuego, or lingering ash in the trailing portion of the plume that lay to the SE.)

At ~32 km (20 miles) distance from the runway, the pilots maneuvered the plane through ~3,000 m (9,700 feet) altitude on a final approach to the airport with the plane's flaps partially extended (at ~15°, which slowed their aircraft to ~260 km/hour (160 mph), its auxiliary power unit (a small jet engine) on, and its landing gear down. Around this point in their descent, pilots saw bright yellow sparks through the windshield lasting a few seconds, a display unlike static electricity, but rather like that from a grinding wheel. This occurred again at 2,500 m (8,200 feet) altitude, but was more intense yet intermittent.

At this time, air-traffic control announced to the pilots that the aircraft landing in front of them had encountered volcanic particulate; they instructed the pilots to abort their landing and climb to 3,350 m (11,000 feet) altitude. Discussions of options and ash avoidance ensued between pilots and air-traffic control; ash had by this time accumulated on the runway, further complicating landing, even for approaches in the opposite direction. The pilots retracted the landing gear, accelerated to ~410 km/hour (~250 mph), began to climb, and after some discussion with air-traffic control, held on a course NE of the airport. They were subsequently cleared to climb to 6,700 m (22,000 feet) altitude and advised to proceed to an alternate airfield.

During the climb, at ~5,800 m (19,000 feet) altitude en-route to the alternate airport, the aircraft encountered volcanic particulate for 10 minutes. Within that interval the plane spent 2 minutes during ascent engulfed in denser and heavier particulate. During that period, window arcing was constant and the beam of their landing lights revealed a conspicuous cloud of reflecting particles. During ash ingestion the engines's speed lacked noticeable fluctuations. The aircraft exited the plume at about 6,100 m (20,000 feet) altitude and landed without encountering additional ash.

Upon landing, the pilots noticed reduced visibility through abraded windshields. Post-flight examination of the airplane revealed heavy damage, requiring the replacement of the engines (US $2 million each) and auxiliary-power-unit engine. (Note, however, that no deterioration in engine power or performance was noticed during the flight.) Other replaced parts included windshields, a heat exchanger, and coalescer bags. Minor damage was seen on the horizontal stabilizer and wing leading-edges.

Volcanic Ash Advisory Statements. The U.S. National Oceanic and Atmospheric Administration (NOAA), Satellite Services Division website contains two archived statements issued by the Volcanic Ash Advisory Center (VAAC) at Washington, D.C. for Fuego on 21-22 May 1999. The statements, issued to the aviation cummunity to warn of volcanic hazards, are intended for an audience accustomed to special terminology (figures 2 and 3). In the interest of advancing understanding of how volcanological and atmospheric data get transmitted to aviators, we offer brief explanations for many of the terms used (figure 2).

Figure 2. The first archived Volcanic Ash Advisory Statement (VAAS) for the 21 May 1999 eruption at Fuego, Guatemala. The boxes contain added notes to explain some of the basic conventions and specific details seen here. This Statement currently appears on the NOAA Satellite Services Division website (see "Information Contacts," below). Local names are frequently anglicized, dropping all accents and other non-English characters (eg. México would be written MEXICO). Later Advisories adopted the abbreviation "Z" (pronounced 'Zulu' by aviators) for UTC, as in 1300 UTC written as 1300Z.

Figure 3. A later Volcanic Ash Advisory Statement (VAAS) for the 21 May 1999 eruption at Fuego, Guatemala. The statement, which was issued the next day, discloses that the eruption had then stopped and the hazard status was lowered. The statement appears on the NOAA Satellite Services Division website (see "Information Contacts," below).

The Washington VAAC received first notification of the Fuego eruption from a routine surface weather observation from Guatemala City at 2000 local time (0200 UTC) on 22 May. They issued the first Volcanic Ash Advisory Statement a half-hour later (figure 2). Six hours later they issued the second Advisory Statement (figure 3). The Advisories were composed by staff of the Satellite Analysis Branch, one of the two NOAA components forming the Washington VAAC (Streett, 1999; Washington VAAC).

The section "Details of ash cloud" first says that the "surface observation from Guatemala City indicate that the Fuego volcano is in eruption" and that no additional information is available and then briefly describes in words observations that came from satellite imagery. The first sentence, "No eruption . . ." is self-explanatory, but highlights a limitation of the method in use that needs to be emphasized to aviators: an eruption may have occurred but its status is not revealed on the imagery. The sentence, "No eruption could be detected due to thunderstorm cloudiness covering the area around the volcano" is self-explanatory. Less clear is the term convective debris. It does not refer to ash; rather, it refers to remnants of thunderstorms. The gist of these latter two sentences is simply that the thunderstorms that covered the area made it challenging or impossible to see the ash on satellite imagery. Central American thunderstorm clouds typically can reach altitudes of more than 12,000 m (40,000 feet), and can mask or obscure airborne ash residing below that level.

Members of the Washington VAAC commented that this eruption demonstrates key problems that can arise when cloudy conditions prevent satellite detection of ash, foiling a primary mode of analysis. In such cases, they rely on ground observers (including observatories and weather observers), pilot reports, and reports from airlines. Thus, their ability to issue useful information in cloudy conditions depends on the quality of communications with local observers, the Meteorological Watch Office, volcanologists, geophysical observatories, and the aviation community.

The Advisory Statement listed México City weather balloon data acquired 1,050 km NW of Guatemala City. In retrospect, the Washington VAAC noted that they generally avoid using such distant sounding data. If a closer sounding cannot be found, they prefer to use upper-level wind forecasts taken from a numerical weather model. In any case, the scarcity of local sounding data presents a challenge to the realistic analysis of airborne ash.

The outlook section says to "see SIGMETS." SIGMETS are the true warnings to aircraft for SIGnificant METeorological events. They are issued by regional Meteorological Watch Offices (MWOs), in this case the MWO (for Guatemala) is in Tegucigalpa, Honduras. SIGMETS were lacking for this eruption; although the Washington VAAC tried to contact the MWO without response. Another complexity confronted at the VAAC is a lack of a single scale for communicating a volcano's hazard status.

Reporting of aviation ash encounters. In personal communications with Bulletin editors, airline personnel stated that many more encounters have occurred than have yet been tallied in publically accessible literature. In accord with those assertions, the 21 May 1999 encounters are absent from reports compiled by the International Civil Aviation Organization (ICAO, 2001). In that document (Appendix I, table 3A, p. I-12) Fuego fails to appear as a source vent for any aircraft-ash encounter. Pacaya is listed for two encounters, in January 1987 and in May 1998 (BGVN 23:05).

Even though the number of encounters was probably under-represented and thus reflects a minimum, ICAO (2001) notes that the international costs to aviation since 1982 summed to well in excess of $250 million. They noted, "In addition to its potential to cause a major aircraft accident, the economic cost of volcanic ash to international civil aviation is staggering. This involves numerous complete engine changes, engine overhauls, airframe refurbishing . . . aircraft downtime . . . [and] volcanic ash clearance from airports and the damage caused to equipment and buildings on the ground."

The incidents here suggest that there has been a strong bias toward under-reporting aircraft-ash encounters. If this tentative conclusion is correct, it implies consistent understatements of the hazard's magnitude. This, in turn, may have thwarted meaningful analysis of how and whether to proceed with designing more robust hazard-reduction systems. Accordingly, resources that could have been devoted to the problem have not yet been committed (see Gimmestad and others, 2001 for a discussion of a prototype on-board ash-detection instrument).

Communication challenges. While much of the aviation community needs to learn about volcanism rapidly, dependably, and with the aid of the Internet, some observers charged with reporting volcanic-ash hazards in Central and South America lack access to basic communication devices like reliable telephones and fax machines. To reduce the risks, the aviation, meteorological, remote sensing, and volcanological communities need to improve their ability to pass critical information to each other rapidly and precisely. The operational systems related to volcanic ash and aviation must transcend numerous boundaries (eg., languages, infrastructure, funding, governments, agencies, air carriers, pilots, aircraft manufactures, etc.). The systems need to portray complex, dynamic processes such as the rapid rise of an explosive plume, or large-scale ash-cloud movement.

Although the infrastructure for ash avoidance is greater than ever, members of the Washington VAAC have told Bulletin editors that they still depend heavily on people on the scene of the eruption to notify them promptly when eruptions occur. They said that thus far in parts of Central and South America a problem has been the expense of communication (eg., by phone, fax, and Internet). They also said that for the same regions the U.S. meteorological database regularly lacks pilot reports. Though serious, these problems have at least been identified and their solutions would appear to lack great technical or economic barriers.

The pilots involved in the May 1999 encounter recommended that far more emphasis be placed on forecasting and avoiding ash plumes. Other pilots cited the need for fast and accurate communications between those who observe eruptive activity and air traffic control personnel.

Issues like these continue to be an important subject at gatherings on the topic of ash hazards in aviation (Casadevall, 1994; Streett, D., 1999; Washington VAAC, 1999). The Airline Dispatcher's Federation (ADF) will participate in a 7-9 May 2002 conference and workshop: "Operational Implications of Airborne Volcanic Ash: Detection, Avoidance, and Mitigation." The gathering will provide the pilot and dispatcher with insights into volcanic ash, including its characteristics, affects on aircraft, detection/tracking, effective warning systems, and mitigation. A "hands-on" exercise will make this the first gathering of its kind to provide lab-style instruction on interpretation of satellite and wind data, and on models of ash trajectory and dispersion. Representatives from the Boeing company, and a host of US government agencies and non-governmental organizations will attend. The workshop will include lectures, demonstrations, laboratory exercises, and a simulated-eruption exercise involving volcanologists, forecasters, controllers, dispatchers, and pilots.

A second international symposium on ash and aviation safety is being planned by the U.S. Geological Survey, organized by Marianne Guffanti. It will be held in Washington, D.C. in September 2003.

Explosions, ash emission, and lava flows during January-February and July 2002

On 4 January 2002, an eruption began at Fuego during 0200-0300. A probable explosion was followed by Strombolian-type ejections and continuous tremor, but no lava flows were visible. Intermittent mild-to-moderate explosions continued during the next few days, producing ash clouds that rose 400-600 m.

In late January, Fuego continued to erupt a lava flow down its E flank. The flow stretched several hundred meters below the summit before falling apart on steep slopes. The toe of the flow calved off about once a minute, but the volume of material was not sufficient to generate pyroclastic flows. Minor amounts of ash were kicked up when the front flow calved. Incandescence from the flow front was visible from Antigua. No explosive activity was observed and only low-level tremor was recorded. A generally white plume was observed.

Based on information provided by Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hidrologia (INSIVUMEH), the Washington VAAC reported that on 1 February at 0930 ash, steam, and lava were emitted from Fuego. An ash-and-steam cloud rose to ~4.5 km altitude and drifted to the SW. No ash was seen on satellite imagery, but a hotspot was visible on infrared imagery. News reports stated that as of 10 February the increase in earthquakes and gas emissions at Fuego led Coordinadora Nacional para la Reducción de Desastres (CONRED) to declare Alert Level Yellow for the departments of Chimaltenango, Sacatepéquez, and Escuintla. On 10 February INSIVUMEH reported that more than 400 explosions occurred at Fuego in comparison to the ~75 daily explosions that had normally occured in the recent past. During the evening, incandescent lava was seen flowing down the volcano's S flank.

Volcanism increased at Fuego on 12 February, with a ~2-km-long lava flow streaming down its flank towards an unpopulated area. Several shelters were set up in the event that the lava flows traveled towards populated areas or if volcanism increased.

A new cycle of eruptive activity began at Fuego on 16 July that consisted of an increase in Strombolian explosions and the occurrence of high-frequency volcanic tremor for 24 hours. On 28 July a thick gray ash cloud drifted 10-15 km to the W. Ash was deposited in the areas of Rochela, Panimaché, Morelia, Santa Sofía, and to the W in Yepocàpa, Chimaltenango. This activity was associated with a collapse of the front of the lava flow in the Las Lajas drainage, which began on 23 January.

On the evening of 29 July the FG3 station registered an increase in seismicity (particularly in continuous tremor) during a 24-hour period. The intensity of the explosions in the crater also increased, and the lava flow reached 2-3 km in length. Early on 2 August the explosions became more vigorous, changed from Strombolian to Vulcanian, and ash columns rose 800-1,400 m above the crater. A column of fine ash extended 4 km W.

Beginning on 2 August, the emanation of gases from the crater diminished considerably, and the SE lava flow decreased in length. COSPEC measurements on the same day revealed that SO2 was at moderate levels (394 metric tons), and had increased since measurements taken on 18 June (319 metric tons) (table 1). RSAM data showed an increase in activity during 26 July-3 August, when values peaked at ~675 RSAM units. After 3 August, RSAM values gradually decreased, reaching a value of ~375 RSAM units by 9 August. In the villages of Panimaché (4 km SW) and Zapote (SE flank) a decrease in water levels coincided with increased fumarole activity and frequency of volcanic tremor.

"Kiwi" Bhatia reported that Fuego erupted almost continuously during 17-23 July. He estimated that the lava flow advanced 30 m or more. Pyroclasts tumbled down the flanks. Strong rumblings during 10-21 August were loud enough to be heard from neighboring farms.

According to Glyn Williams-Jones (HIGP/SOEST), GOES hot-spot monitoring may indicate a potential cyclical nature to thermal activity observed at the volcano. In order to facilitate and automate GOES monitoring, a new comparison technique developed by Wright and others (in review) is being tested. A correlation term (R2) compares the peak radiance of a given pixel with the mean background radiance. Changes in activity can be recognized due to their sudden lack of correlation. This technique can be illustrated by the poor correlation (R2 significantly less than 0.9) for the 28 July and 2 August ash emissions (figure 4). From August 19 onwards, activity appears to have returned to "background" levels (i.e., R2 greater than 0.9).

Jacquelyn Gluck reported that visual observation during the afternoon of 25 August and at night on 26 August revealed no activity. No incandescence was seen by observers on high points in Antigua looking to the SW.

Explosions, ash emission, and lava flows took place during January-February and July 2002 (BGVN 27:08). MODIS thermal alerts were recorded monthly throughout 2002. CONRED reported that during the last 3 months of 2002, a change in behavior at Fuego was characterized by an increase in Strombolian activity. Ash emission and pyroclastic flows threatened communities to the SW, which prepared for evacuation (figure 5). This report covers the period of 26 December 2002 through mid-January 2003.

Figure 5. This condensed-format map of Fuego hazards was intended as a poster when created by the Guatemalan agency CONRED. North is towards the top; the original map key and credits are truncated from this version. The map shows six different hazard zones with a gradation of expected hazards, as well as some of the critical close-in population centers and their suggested departure routes. The large population center Antigua lies off the map, 17 km NE of Fuego's summit. Courtesy of CONRED.

According to news reports, an explosive eruption and partial crater collapse occurred on 26 December 2002 around 0905. An ash cloud was generated that reached ~2 km above the volcano and drifted W toward the Yepocapa region. Neither damage nor injuries were reported.

The Washington VAAC reported that an eruption began at Fuego on 8 January 2003 around 0500. According to INSIVUMEH, as of 1100 that day the eruption continued with ash explosions and lava flow emission. A steam-and-ash column rose to 5.7 km altitude and drifted to the W. In addition, two small-to-moderate pyroclastic flows traveled down the Santa Teresa river valley. Seismic signals continued to show evidence of magma ascent, but fewer in number with 15-25 explosions per minute recorded. This suggested continued effusive emissions for a number of hours. During the eruption, ash fell in an elliptical area chiefly W of Fuego; other events included rumbling, and fumarolic activity. CONRED stated that the Alert Level was raised to Orange and several people were evacuated from the town of Sangre de Cristo. According to a news report volcanism decreased the following day, so the Alert Level was lowered from Orange to Yellow.

INSIVUMEH reported that as of 19 January moderate eruptions continued at Fuego that produced ash clouds to 1.5-3 km altitude. Ash drifted to the S and SW, depositing fine ash in the areas of Rocela, Panimache, and Palo Verde. In addition, incandescent avalanches traveled down canyons on the volcano's flanks. Table 2 shows ash advisories issued for Fuego by the Washington VAAC during January.

Satellite imagery showed a vivid hot spot. A possible ash plume was observed moving W from the summit at 1545Z. By 1615Z the narrow plume extended ~18 km to the W of the summit.

08 Jan 2003

2010

Satellite imagery through 1945Z showed a larger eruption occurring with ash estimated to FL200 (6 km). The bulk of the ash was moving N but some moved W. The initial ash plume had detached and was moving W toward the coast.

09 Jan 2003

0200

Ash was not visible in nighttime infrared or multispectral imagery. The last visible image of the day showed ash to the W and NW of the summit moving at 18-28 km/hour. Guatemala City airport reported continuing eruptions.

09 Jan 2003

0755

Ash was not visible in infrared of multispectral imagery through 0715Z. Imagery showed a strong and persistent hot spot. Guatemala City airport reported continuous eruptions.

09 Jan 2003

1400

Ash was not visible in infrared or multispectral imagery through 1315Z. A persistent strong hot spot continued in shortwave imagery.

09 Jan 2003

1915

Ash too thin to be detected in satellite imagery. An occasional hot spot was detected in short wave imagery.

Ash not identifiable in satellite imagery. Surface reports from Guatemala city through 2100Z continued to indicate that the volcano was active. A hot spot continued to be observed in satellite imagery.

12 Jan 2003

0400

Ash not identifiable in satellite imagery. No further reports from Guatemala. Hot spot continued to be observed in satellite imagery.

12 Jan 2003

1030

Ash not identifiable in satellite imagery. Surface reports from Guatemala City indicated that Fuego was active. An intermittent hot spot was seen in satellite imagery.

12 Jan 2003

1615

Ash not identified in satellite imagery and no hotspot was seen at the summit. Surface reports indicated continuing activity.

20 Jan 2003

0430

A report from the Guatemala Volcano Institute indicated that ongoing activity produced an ash cloud to 2 km above the summit (~5.8 km altitude) moving S and SW. Multi-spectral imagery showed the ash in a 18-km-wide line extending ~33 km from the summit. The report also indicated that ash was falling in the areas of La Rochela, Panimache, and Palo Verde.

20 Jan 2003

1030

Ash plume became diffuse and difficult to see on multi-spectral imagery. Around 530Z another puff of ash was seen moving to the SW and an intermittent hotspot was visible for the past few hours.

20 Jan 2003

1630

Exhalation of ash and steam at 0615Z. Ash plume diffuse and difficult to see on satellite imagery.

Observations during 3-13 January 2003. Craig Chesner and Sid Halsor reported continuous low-level volcanic activity and one larger event at Fuego during a 10-day site visit. Nearly continuous Strombolian-type spattering and fountaining were observed during the night of 3 January. Bombs and blocks, ejected up to several tens of meters above the summit vent, fell on the upper flanks. No ash was observed during this activity, although ashy trails were generated from ejecta tumbling down the steep southern and eastern slopes of the volcano. On 4 January, no lava fountaining was observed, and activity was characterized by steady and passive emission of a gas plume.

Energetic fountaining and spattering were observed during the night of 5 January from a vantage point on the summit of nearby Agua volcano. Fourteen Strombolian explosions occurred at intervals of 5-61 minutes during 5 hours of continuous observation. These explosions ejected incandescent material ~100 m above the cone, showering the upper flanks with blocks and bombs. Typically, each explosion was accompanied by a loud detonation and an ash plume, and led to several minutes of vigorous fountaining. This activity continued during the morning of 6 January, but by evening, no incandescent activity was apparent at the summit vent.

On the morning of 7 January, a new lava flow was noted on the southern flank, and ash trails generated from spalling blocks suggested that it was active. In the evening, vigorous lava fountaining and spattering had resumed, and the lava flow was seen descending from the summit area to the S. A nearly continuous cascade of pyroclasts produced incandescent rock falls on the upper flanks of the cone.

At 1030 on 8 January, an expansive plume of ash had developed over the summit area. Concurrent fountaining and pulsating eruptions of ash were observed from a vantage point near Alotenango, a few kilometers NE of the volcano. By 1100, the eruption column was broadening at its base, darkening in color, and extending to considerable height above the summit. The most intense phase of the eruption occurred roughly between 1145 and 1215 (figure 6). During this time, loud rumbling and swashing-like sounds accompanied continuous fountaining and frequent, energetic eruptions of ash. A bright incandescent fire fountain, several tens of meters high, was clearly observed at the base of the ash column. Twice during this time period, lateral ash columns, presumably associated with pyroclastic flows, were noted descending towards the W. A convective column engulfed the summit area and appeared to rise several kilometers to an altitude of ~2-3 times the height of the cone.

Figure 6. Image of Fuego eruption taken on 8 January around 1200. View looking W from about 10 km away. The eruption cloud was dispersed westward and the ground-hugging smaller cloud just W from the summit area may have been associated with reported pyroclastic flows. Courtesy Sid Halsor.

By 1245, eruptive activity appeared to subside with eruptions becoming less frequent and gradual lightening in color of the ash cloud. Throughout the afternoon, the ash cloud drifted westward and dispersed ash-laden air over a broad region. A circumnavigation of the volcano during the afternoon indicated no detectable ash fall along the dispersal axis at a distance of ~9 km. However, a slight discoloration of vegetation was noted to the E of Yepocapa. Intermittent low to moderate ash eruptions continued throughout the day and summit fountaining was observed at night. The following morning (9 January), no visible activity was noted over a brief observational period. However, the summit area surrounding the vent had clearly changed, being asymmetrically higher to the NW. From 10-13 January, activity was characterized by periodic low-level Strombolian explosions and associated ash plumes. These plumes could be seen from as far away as western El Salvador.

Explosive and effusive activity, last reported through January 2003 (BGVN 28:01) has continued through October 2003. Plumes identified on satellite imagery between April and September 2003 were described in aviation advisories issued by the Washington Volcanic Ash Advisory Center (VAAC). Regular reports of daily activity provided by the Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hidrologia (INSIVUMEH) on their website have been summarized for many days in the second half of October.

Activity during April-September 2003. The Washington VAAC reported that on 28 April 2003 Fuego generated intermittent ash eruptions. One cloud was observed at ~ 7 km altitude moving SW at 19-29 km/hour. On 2 May the VAAC reported possible ash around the summit, but as of 1515, none was visible. INSIVUMEH indicated that although Fuego was active with explosions, most ash was confined to near the summit.

On 29 June INSIVUMEH reported a moderate eruption during 1745-2200 that consisted mainly of lava effusion. Lava flows were observed on the E flank, in the Lajas, Jute, and Barranca Honda ravines. Avalanches generated sounds similar to a locomotive, with strong rumblings and acoustic waves. Fuego's Observatory 2, on the SW flank, reported 2 cm of ashfall. Ashfall also occurred in San Pedro Yepocapa, Patulul Suchitepequez, Cocales, and villages W and SW of the volcano. At about 2335 there was a reduction in seismic activity at the Fuego 3 station.

INSIVUMEH reported on 1 July that explosive activity continued with weak to sometimes strong explosions ejecting grayish ash up to 900 m above the crater, with occasional degassing sounds and rumblings. Pyroclastic-flow material moved into the W-flank Seca and Santa Teresa valleys, 1.5 km from the village of Sangre de Cristo. A pyroclastic flow was reported by the Washington VAAC at 1130 on 9 July. INSIVUMEH reported strong explosions with ash to 2 km above the summit, a plume extending 5-7 km W, and ashfall to the W and SW. GOES-12 imagery showed a 3.7-km-wide plume extending ~ 11 km W.

The Washington VAAC reported on 7 August that a brief puff of ash was ejected at about 1600; the small plume moved to the NW and dissipated by 1745. On 28 September the Washington VAAC, based on visible and multi-spectral IR techniques, reported an ash eruption at about 1100. This plume, which was ~ 5 x 5 km, moved S toward the coast and was no longer discernable on imagery by 1400. A second ash emission between 1415 and 1432, with an approximate altitude of 6 km, was partially obscured by clouds.

Activity during 15-30 October 2003. On 15 October INSIVUMEH reported the continuation of eruptive activity, with degassing and small rumbling sounds. Incandescence was seen above the crater at night. The ejected ash was dispersed around the volcanic edifice. A small eruption that began at 0007 on 17 October ended at 0040 after five moderate explosive pulses, each 2-3 minutes in duration, generated thick columns of grayish ash ~ 1,500 m high. Before and after this eruptive event moderate and strong explosions caused rumbling and shock waves felt at the OVFGO and FG2 observatories. Small incandescent avalanches moved towards the Santa Teresa valley.

Harmonic tremor was registered at the FG3 station at 1630 on 20 October. On 21 October, INSIVUMEH reported explosions after 0350. The majority were strong, expelling abundant incandescent material. Ash columns caused small and moderate avalanches, mainly in the Santa Teresa and Trinidad valleys, and occasionally in the Taniluyá. Shock waves were felt by communities around the volcano. Slight ashfall occurred in the Morelia and Santa Lucia villages located 7 and 10 km, respectively, SSW of the active crater.

On 23 October, INSIVUMEH reported moderate, weak and occasionally strong explosions producing grayish and blackish plumes up to one km high. Moderate and strong explosions generated rumbling and lava flows that traveled toward the Santa Teresa and Trinidad valleys. Ashfall occurred in the upper portion of the Fuego-Acatenango complex. At 0945 a strong explosion, lasting 1.5 minutes, produced a thick ash cloud that reached a height of ~ 1 km and dispersed to the SW. Two short pulses lasting 45-60 minutes between 1200-1300 and 1800-1900 on 23 October generated a series of 7-9 moderate explosions that produced a grayish column to ~ 1 km over the central crater.

A strong explosion at 0910 on 27 October was preceded by five moderate explosions at intervals of 3-7 minutes that produced gas clouds and ash 700 m high. The first event produced a heavy ash column of a height of ~ 1 km which dispersed to the SW. An explosion at 0625 caused a pyroclastic flow toward the Trinidad and Santa Teresa valleys, and produced light ashfall in the village of Sangre de Cristo. On 29 October INSIVUMEH reported predominantly weak and moderate explosions 1-3.5 minutes long with gas-and-ash columns up to 1 km high. The last of these produced ashfall, shock waves felt at OVFGO, and avalanches of incandescent material toward the Santa Teresa and Trinidad valleys.

On 30 October an effusive eruption during 2300-0600 produced incandescent lava fountains 75-100 m high with pulses of 5-6 minutes, changing to fountains ~ 50 m high and 15-20 minutes long. A short lava flow descended SW from the crater rim, reaching ~ 250 m in length and splitting into three short branches. Short avalanches and pyroclastic flows descended to the top of the Santa Teresa valley. The eruption produced moderate to weak sounds lasting ~ 2 minutes. At dawn, a thick fumarolic plume was observed blowing NW. There was no ash emission during this activity, but at 0625 hours a small explosion sent a column of gas and ash ~ 400 m high. The seismic station at FG3 registered harmonic tremor (2-4 mm amplitude).

Explosions and lava flows at Fuego continued after October 2003 (BGVN28:10). Similar activity prevailed through 2003 and 2004. This report discusses events during November-December 2003 and includes a table summarizing Fuego's 2003 behavior (table 3). A future report will discuss 2004 activity and will include a map showing critical place names. Several pyroclastic flows occurred in 2003.

Tremor was common and at times abundant during 2003, including in the last two months of the year. On 21 November, almost continuous harmonic tremor was detected for a span of 21 hours. On 23 November intervals of tremor lasted between 0.5 and 3 hours.

The Washington VAAC archive contains 48 ash advisories on Fuego. The number of these advisories were as follows, during the stated months of 2003: 14 advisories in January (on the 8th, 9th, 11th, 12th, and 20th); 11 in April (on the 17th, 28th, 29th, and 30th); eight in May (1st and 2nd); three in June (30th), six in July (1st, 9th, and 10th), two in August (7th), two in September (29th); and two in October (9th). The most impressive plumes depicted in satellite-based graphics were for 28 April-1 May 2003, when they often stretched well out to sea, reaching ~ 160 km SW from Fuego. Otherwise, the graphics generally depicted much smaller plumes, in some cases very local ones. The graphic for 28 September showed small plumes from Fuego as well as simultaneous ones from Pacaya and Santa María.

Fuego remained active into 2005, although this report focuses on the interval 31 December 2003 through 11 May 2004. A previous report discussed activity through the end of 2003 (BGVN 29:11); this report, based mainly on information from INSIVUMEH (Instituto Nacional de Sismologia, Vulcanologia, Meterologia y Hidrologia) covers the interval from end of 2003 to 11 May 2004.

Figure 7 is a map of the Fuego-Acatenango region, emphasizing drainages and settlements frequently mentioned in activity and hazard reports. Fuego is moderately close to the centers of some of Guatemala's largest cities, including the Capital (2-3.5 million inhabitants, ~ 40 km NNE of Fuego's summit) and Antigua (~ 32,000 inhabitants, ~ 18 km NNE).

Figure 7. A sketch map of Fuego and adjacent Acatenango centered several kilometers S of these edifices. Numerous drainages emerge from the stratovolcano, their paths trending radially outward as well as in many cases curving decidedly S with distance from the volcano. Abbreviations 'R.' and 'Q.' apply to the Spanish-language terms Río (river) and Quebrada (canyon, and in this region these are often steep-sided, essentially gorges). 'F' stands for finca (farm or plantation, many of which grow the renowned Antigua coffee). A few contours are shown around these volcanoes (labeled in meters above sea level). The Fuego-Acatenango complex also contains two smaller (unlabeled) topographic highs, each one a few kilometers N of the better known peaks (i.e. N of Fuego, Meseta, and N of Acatenango, Yepocapa). Several towns off the map's margins are indicated with arrows and distances. Compiled by Bulletin editors from topographic maps.

CONRED, the Guatemalan hazards agency (Cordinadora Nacional para la Reducción de Desastres) posted hazard information on their website, in part using a map format noting conditions seen from various perspectives. For example, the map issued for 9 January 2004 (during the largest crisis of the interval), included a title, a legend, a summary of critical hazards-oriented observations. One portion of the 9 January map reported a local wind velocity, N-NW at 12-18 km/hr, and the occurrence of fine and very fine ash falling within 5 to 15 km of the crater. The map also included key radio base stations and for each, a summary of the day's message content.

Many early 2005 observations were hampered by rainfall. Table 4 summarizes numerous INSIVUMEH daily reports during February, but for the bulk of the entries, it chiefly presents Smithsonian/USGS Weekly Reports to portray longer time spans.

Table 4. Samples of Fuego activity during 31 December 2003 through 11 May 2004. Summaries based largely on Smithsonian/USGS Weekly Reports are shown as multi-day intervals (marked with an asterisk, "*"). Most of the reported eruptions in column 3 were ash bearing. Courtesy of INSIVUMEH.

Small-to-moderate explosions. The highest rising ash plume was produced from an explosion on 29 January. The plume reached above the crater and was accompanied by avalanches of volcanic material down Barranca Seca. A small amount of ash fell in Panimache village and possibly in Santa Sofia. On 31 January two small collapses in the S edge of the central crater produced small avalanches of lava blocks.

16 Feb 2004

0.3-1 km, SW

Audible acoustic shock waves. Ashfall on upper edifice.

17 Feb 2004

--

Incandescent avalanches rose 200 m at night, but some traveled into the drainages of the Taniluya, Ceniza, and Zanjon Barranca Seca. A mudflow descended the Quebrada Santa Teresa (on Fuego's W-SW sides) carrying blocks up to 2 m in diameter. During 0855 to 1140 Fuego produced 10 explosions characterized as strong, resulting in warnings to civil aviation authorities. Ashfall on W- and SW-flank communities.

18 Feb 2004

1.5-1.7 km

A rapid succession of 15 early morning explosions at 10- to 30-second intervals were heard up to 8 km distant from the summit. Incandescent material landed on many of the upper slopes. Judging by the quantity and weight of ash fall, INSIVUMEH inferred that the eruption caused substantial changes in the summit area. Finer ash fell for 10 to 15 minutes on Finca Sangre de Cristo and environs. Besides aviation safety, concerns included drinking-water contamination. Ashfall up to 8 km from summit.

20 Feb 2004

1.5-2 km; light to moderate S winds

Loud outbursts and incandescent avalanches down the W-flank valleys of the Seca, Taniluya, and Trinidad rivers, and to lesser extent down SE-flank valleys of the Las Lajas-El Jute rivers. Ash-bearing emissions came from the central crater at 4- to 9-minute intervals. Some traces of ash noted to the N, in the Capital.

25 Feb-02 Mar 2004*

~1.7 km

Weak-to-moderate explosions continued at Fuego, producing plumes above the crater. Avalanches of volcanic material traveled down several ravines, including Trinidad, Ceniza, Santa Teresa, and Taniluya (to the W). Explosions on 28 February deposited small amounts of fine ash in the village of Sangre de Cristo, and explosions on 29 February deposited ash W and SW of the volcano in the villages of Yepocapa and La Cruz.

04 Mar-08 Mar*

~1.5 km

On 5, 7, and 8 March avalanches of incandescent volcanic material traveled as far as 1.5 km down several ravines, including Seca, Taniluya, Ceniza, and Trinidad. Explosions on the 7th and 8th deposited ash 6-10 km from Fuego, including in the villages of Sangre de Cristo and Panimache.

10 Mar-16 Mar 2004*

~1.7 km

Explosions; incandescent avalanches as far as 600 m down ravines on the volcano's W, SW, and S flanks; ash fell in W- to SW-flank settlements from Sangre de Cristo to Panimache and Finca Morelia.

17 Mar-23 Mar 2004*

~1.3 km

Volcanic material traveled down the Seca ravine; ash fell in the village of Sangre de Cristo.

24 Mar-30 Mar 2004*

~1 km

Three strong explosions were recorded on 26 March; they caused incandescent avalanches in the Zanjon Barranca Seca and Trinidad ravines. On 29 March two explosions within 7 minutes produced ash plumes. A lahar occurred on 29 March in the Zanjon Barranca Seca ravine.

31 Mar-06 Apr* 2004

~1.2 km (5 April, drifting SSE)

Lahars flowed down Seca Ravine on 30 March, and passed near the village of Sangre de Cristo on 3 April. Incandescent avalanches descended several ravines, including Santa Teresa, Ceniza, and Taniluya.

Ash-bearing explosions. On 28 April, an explosion produced an ash plume above the volcano, and ash was deposited ~4 km SW of the volcano in the villages of Panimache I and Panimache II. In addition, a small volcanic avalanche traveled W toward the Santa Teresa ravine.

05 May-11 May 2004*

--

Explosions chiefly produced gas-and-ash clouds. On 5 May a small lahar traveled to the W down Seca ravine.

From the table, the pattern emerges of ongoing emissions with frequent plumes to 1 km and occasional higher plumes (several to ~ 2 km and one to ~ 3 km). Similar to previous months, the reports frequently mention dislodged lava blocks and mass wasting of volcanic materials.

The highest plume found in available reports of the interval occurred on 8 January 2004, when an ash plume rose ~ 3 km over the summit. Traces of ash fell in the Capital during this episode.

Fuego began its 8 January eruption around 1500 to 1600, expelling thick, broad columns of gases and ash to ~ 3 km above the crater. There were 25-30 explosions a minute accompanied by loud rumbling noises and acoustical shock waves felt 12 km away. Although no evacuations were ordered, settlements on the upper flanks were considered at risk, including San Andrés Iztapa, Chimaltenango, Comalapa, San Martín Jilotepeque, San José Poaquil, and Yepocapa.

The Washington VAAC added these observations: "[GOES 12] satellite imagery shows two plumes moving away from the volcano. The higher plume extends approximately 75 nm [~ 140 km] to the [N] and is estimated to be around FL250 [shorthand for 25,000 feet altitude, ~ 8 km]. A lower plume extends approximately 70 nm [126 km] to the [W] and is estimated to be up to FL190 (19,000 feet altitude, ~ 6 km). Hot spot activity has been fairly strong and constant over the past several hours."

A 20 February report described continued vigorous activity; ash emissions from the central crater rose to heights of 1.5-2 km above the summit (table 1). Light to moderate winds again blew the ash N and some traces fell in the Capital.

Fuego was previously discussed in BGVN 30:08. This report discusses ongoing developments at Fuego since July 2005 and through December 2006. In general, the volcano erupts vesicular, olivine-bearing basaltic lava flows. They traveled from the central crater hundreds of meters down the S, SW and W flanks, and the lava flow fronts released occasional blocky avalanches of incandescent material. The latter process is generally omitted from the rest of this report unless the avalanche(s) were particularly noteworthy, as in cases where pyroclastic flows were also noted.

On 17 July 2005, an ash plume ~ 3.5-4 km high accompanied small pyroclastic flows down Santa Teresa and Taniluyá ravines. This activity continued sporadically through October 2005.

At 0602 on 27 December, a pyroclastic flow descended S. Ash fell S of the volcano in the port of San Jose. Later that day, lava flows extended 1.2 and 1.3 km, and pyroclastic flows descended 1.8 and 2 km down the Taniluyá and Seca ravines, respectively. Lava flows also traveled W toward Santa Teresa ravine, and SE towards the Jute and Lajas ravines. An ash plume rose ~ 7.6 km, and a small amount of ash fell W and SW of the volcano in the villages of Morelia, Santa Sofía, Los Tarros, and Panimaché (~ 7 km SSW). This activity continued through 29 December with more lava flows and bombs. The emissions hurled incandescent lava clots ~ 75 m high, spawned lava flows, and generated a dark plume rising to ~ 1 km above the crater rim.

January 2006 activity was essentially a continuation of December's with moderate-to-strong explosions and incandescent lava ejecta hurled ~ 40 m high. Explosions could be heard 25-30 km away. The explosions were accompanied by rumbling sounds and acoustic waves that shook windows and doors in villages near the volcano. Ash plumes rose ~ 1 km to ~ 1.5 km. On 22-23 January, there were Strombolian lava ejections rising ~ 100 m above the crater rim accompanied by block avalanches down the SW flank.

During February and March 2006, explosions moderated but activity continued. Weak-to-moderate explosions occurred; shock waves were sometimes felt in villages near the volcano. On 6-7 March, ash emissions up to ~ 4.6 km altitude were visible on satellite imagery.

The only activity reported in August occurred on the 16-17th, when ash explosions reached 300-800 m above the crater rim, and explosions of incandescent material produced avalanches that descended 300-500 m SW towards the Cenizas, Taniluyá, and Santa Teresa river valleys.

The latter half of September 2006 continued the characteristic previous activity with explosions that sent incandescent lava 75-100 m above the crater rim and that generated hot avalanches SW towards the Taniluyá River.

On 15 November, lava flows traveled about 150 m SW, and avalanches occurred from the lava-flow fronts. On 17 November, three out of seven explosions propelled incandescent material 100 m above the central crater rim. Relative quiescence followed through December 2006.

Moderate Strombolian eruptions, including pyroclastic flows, continue into early 2008

Eruptive activity has continued at Fuego between January 2007 and early February 2008. Typical activity during this interval consisted of explosions that generated ash plumes up to ~ 2 km above the summit (~ 6 km altitude) and caused local ashfall (reported up to ~ 15 km away, but from one eruption, ~ 25 km away). Strombolian eruptions, avalanches, and lava flows up to ~ 1.5 km long were also commonly reported. Pyroclastic flows traveled up to ~ 2 km. Blocks detaching from the front of the flows and bouncing downslope were often incandescent. Satellite imagery often detected hotspots. Shock waves and rumbling or loud noises, sometimes described as similar to a passing airplane, were commonly noticed. Out last report discussed events through December 2006 (BGVN32:11).

Details included in the text below were provided by the Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia (INSIVUMEH), the Coordinadora Nacional para la Reducción de Desastres (CONRED), and the Washington Volcanic Ash Advisory Center (VAAC).

The photographs included in this report are by Richard Roscoe, who on his website (www.photovolcanica.com) features more Fuego photos than we can include here. He also includes a brief animation of a small Fuego eruption. His site also provides a beginner's guide to volcano photography as well as cautions about safety and trekking in the area. All of his photos are used with his permission. They were taken during 29-31 December 2007. A companion site by his colleagues M. Rietze and Th. Boeckel also describes their photo excursion. Figures 8-10 are broadly representative of the kinds of eruptions common at Fuego during the reporting interval, and they provide a feel for the regional setting and geography.

Figure 8. A view of Fuego in eruption as seen from the city of Antigua. Note twin church spires along the photo's lower margin. Fuego (erupting at left) is only one of several volcanoes in this photo; progressively farther towards the right peaks consist of Meseta, Acatenango (highest), and Yepocapa. This copyrighted photo is from around 29-31 December 2007. Used with permission of photographer Richard Roscoe.

Figure 9. An explosive plume rising vertically above Fuego's summit on 29 December 2007, with wisps of falling ash visible on the right side. The photo was taken from Antigua. Copyrighted photo by Richard Roscoe.

Figure 10. Incandescent ejecta from Strombolian eruptions of Fuego taken from the N on Acatenango volcano (~ 4 km elevation). The exact date was surmised from text as 30 December 2007. The shape of Fuego's summit has been modified by the growth of a sharp peak, presumably due to the accumulation of spatter and cinder. The night-time exposure also captured in the background the lights of towns on the Pacific coastal plain to the S. Copyrighted photo by Richard Roscoe.

During 4-5 January 2007 gas-and-ash clouds rose to 4.2-4.8 km altitude and constant incandescent avalanches from the central crater and a lateral crater ~ 70 m from the S edge of the central crater descended SW towards Taniluyá ravine. Fine ashfall was noted in areas S and ~ 9-15 km SW of the summit. On 12 January there was explosive ejecta and ash plumes up to 4 km altitude. Incandescent material was propelled up to 75 m above the summit and incandescent blocks rolled W towards Taniluyá ravine and Santa Teresa ravine, and S towards Cenizas ravine. Explosive activity was reported again during 21-29 January when incandescent material and blocks were ejected 100 m above the summit; blocks rolled ~ 500 m S and SW. On 26 and 29 January glowing blocks from lava-flow fronts rolled S towards Cenizas ravine. During an overnight visit to a neighboring summit, Craig Chesner and Sid Halsor saw Strombolian eruptions at roughly half-hour intervals.

No activity was reported after late January until 9-13 March 2007, when lava flows were noted extending ~ 100-150 m W toward Taniluyá ravine and explosive ash plumes rose to 4-4.2 km altitude. On 12 March glowing material was ejected ~ 15-20 m above the central crater. Lava flows on 15 March and explosive incandescent ejecta thrown 200 m above crater rim were accompanied by an ash plume. The longest lava flows traveled ~ 1.5 km W toward Taniluya ravine. Similar activity continued the next day, with previous lava flows advancing and new flows seen in different ravines. Pyroclastic flows also occurred, ash plumes rose to 4-6 km altitude. Shockwaves were felt ~ 15 km away, and Strombolian eruptions propelled glowing tephra 300 m above the summit. Two pyroclastic flows traveled about 800 m; one NW, and another W and SW. During most days 21-27 March Fuego emitted explosive gas-and-ash plumes that rose to ~ 4.7-5.1 km altitude, causing ashfall in areas 5-8 km SSE and 9 km W. On 24 March explosions were followed by lava blocks rolling down the W flank toward Taniluyá ravine. Similar activity on 26 March caused ashfall in areas 10-25 km to the W and SE.

The next reports of activity, during 20-23 April, were of lava flows, pyroclastic flows, explosive incandescent ejecta 50-75 m above the vent, and a gas-and-ash plume up to 4 km altitude. Incandescent material descended 300 m down the S and W flanks. The Washington VAAC reported that an intense hotspot seen on satellite imagery on 21 April was likely caused by a lava flow to the SW. On 23 April a pyroclastic flow and incandescent avalanches traveled down SE and SW ravines; ash explosions caused light ashfall in areas S.

Observations during 17-19 May were of fumarolic emissions ~ 600 m high along with active lava flows extending ~ 100 m SW toward the Taniluyá ravine and ~ 500 m SW toward the Cenizas ravine. The lava flow from the edge of the central crater continued on the S flank (~ 150 m long); landslides of blocks of incandescent material spalled from the front of the flow into the Taniluya ravine. Activity the following week, 26-27 May, consisted of explosive ejecta ~ 100 m above vent, gray steam-and-ash plumes up to 4-4.6 km altitude, and block avalanches to the S and SW. On 28 May the lava flow on the S flank continued to advance and produce incandescent blocks that rolled W in Taniluya ravine. Explosive incandescent ejecta was seen on 29 May, along with lava flows that extended ~ 400 m SW toward Cenizas ravine and incandescent material rising tens of meters above the vent.

On 1-2 August, pyroclastic flows occurred and explosive ejecta was thrown 50-75 m above the crater rim; an ash plume rose to 5.3 km altitude. Incandescent avalanches traveled 500-700 m down the S and W flanks. On 2 August, a moderate eruption produced a pyroclastic flow that traveled ~ 2 km SSW down the Cenizas ravine. A resultant plume produced ashfall S, SW, and W for several minutes.

On 8-9 August, pyroclastic flows and explosive Strombolian activity occurred with a gas-and-ash cloud to 4.4-5.6 km altitude. This eruption was visible from the city of Antigua, even though the resulting lava flows primarily traveled down the S and W flanks, which were on the side opposite from Antigua. Clouds obscured the view of possible E-flank lava flows. Ashfall was reported in areas to the W. Lava flows and related detached blocks traveled 1.5 km down Cenizas ravine to the SW. Several pyroclastic flows descended the flanks. Ashfall was reported in villages to the W, SW, and S.

On 10-13 August, small explosions and ash plumes rose up to 4.3 km altitude. 11 August behavior was characterized by weak explosions that expelled gray ash to 500 m above the crater. On 27 August, lahars carried tree trunks, branches, and blocks down the Lajas drainage to the SE. On 28 August, explosive ash plumes rose to 4.1 km altitude. On 31 August, a lahar 8 m wide and 1.5 m thick descended W down the Santa Teresa ravine.

On 3-4 September, explosive ash plumes rose to 4.5 km altitude. On 3 September, fumarolic plumes rose to 4 km altitude and a 300 m lava flow traveled W down the Taniluya drainage. There were also avalanches in the Cenizas ravine. On 21 September explosions of gray ash rose to ~ 5.8 km altitude and incandescent pulses in the crater rose to 75 m with avalanches in the S and SW flank. On 24 September 2007, moderate and strong explosions occurred, accompanied by ash plumes extending up to 900 m above the crater, and constant degassing sounds for periods of up to 20 min. On 5 October, weak to moderate incandescent explosions occurred, accompanied by ash plumes up to 800 m above the crater, and degassing sounds. Block avalanches were noted in the Taniluyá and Santa Teresa ravines.

On 10 October, weak to moderate explosions occurred, the largest accompanied by ash plumes that rose to 4-5 km altitude. Avalanches from cone building in the inner crater went W into the Taniluyá and Santa Teresa ravines.

On 12 October, INSIVUMEH reported that explosions from Fuego produced ash plumes that rose to altitudes of 4.2-4.8 km and caused ashfall in areas to the W. The explosions were accompanied by rumbling, and degassing sounds; shock waves were detected up to15 km away. The Washington VAAC reported a thermal anomaly on satellite imagery along with ash plumes that drifted W and NW.

According to Washington VAAC, satellite imagery detected multiple ash "puffs" emitting from the volcano between 24-30 October. They also reported ash plumes on 20 November (4.6 km in altitude) and 29 November. Additional weak to moderate explosions occurred on 7 December and 12 December, expelling ash and causing degassing sounds. Shock waves were noticed up to 15 km away.

On 15 December, Fuego generated a significant ash-and-steam plume that was observed from Antigua and Guatemala. It also produced a considerable flow of ash (and possibly lava) down its E slopes. According to the Washington VAAC, satellite imagery detected a thermal anomaly on 15-16 December. Thereafter, Fuego's activity declined to normal levels, although a few moderate explosions continued, along with an occasional ash plume. An ash cloud from Fuego was observed on 21 December and 26 December 2007.

For 11 January and 24 January 2008, INSIVUMEH reported weak explosions from Fuego that produced ash plumes that rose to altitudes of 4-5 km. Small avalanches of blocks traveled W toward the Taniluyá ravine. Based on reports from INSIVUMEH, CONRED reported on 28 January that the Alert Level was lowered to Green. On 30 January, satellite imagery detected a narrow plumes of gas and possible ash. On 4 February, satellite imagery detected ash plumes that rose to an altitude of 5 km.

Many small ash plumes and some lava flows during 2008-2009; instrumented study

The current eruption from Fuego, located ~40 km WSW of the country's main airport (La Aura) and 17 km NE of the historic city of Antigua, has been ongoing since 2002. The Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia (INSIVUMEH) monitors this volcano, providing regular observations. During the current reporting interval, 11 January 2008-12 January 2010, minor ash plumes were common, typically rising several hundred meters above the summit (tables 5 and 6). Some were incandescent. Plumes often drifted 5-15 km from the vent and residents in the region sometimes noted noise and shock waves. Observers occasionally saw avalanches and lahars, and sometimes an active lava flow traveled ~100 m from its vent. On 30 January 2009 observers saw incandescent material ejected 50-100 m above the crater and avalanches from the crater rim descended multiple ravines.

Observations. A report from Michigan Technological University described multi-instrument fieldwork during 9-21 January 2009 (Nadeau and Dalton, 2009), work often amid conditions of poor visibility. The authors also credited seven other people (from INSIVUMEH and PCMI; see Information Contacts) who participated in the campaign. One of the instruments deployed was an ultraviolet (UV) camera that enabled researchers to measure SO2 emission rates with high temporal resolution. They also took concurrent seismic and infrasonic acoustic measurements, some mini-DOAS measurements, and they recorded their visual observations of volcanism. A similar campaign occurred in January 2008.

During this fieldwork, activity was dominated by passive degassing accompanied by intermittent tephra eruptions of variable size (figure 11). Explosions ranged from small puffs of ash that mixed with the passive gas plume to larger, convective columns with ejected bombs.

Figure 11. Passive degassing (left) and an explosion (right) at Fuego, December 2008-January 2009. From Nadeau and Dalton (2009).

During 9-21 January 2009, the UV camera was placed on Meseta ~1 km from the erupting vent (figures 12 and 13). An array seismo-acoustic stations was also deployed around the circumference of the vent for full azimuthal coverage. Thick clouds prohibited visibility on most days, resulting in collection of imagery on only 3 dates (12, 14, and 21 January). On 21 January several stationary mini-DOAS (differential optical absorption spectroscopy) scans of the passively degassed plume were also made for comparison with SO2 retrievals from camera images.

Figure 12. Vertical aerial photo the Fuego summit (steaming, near the bottom) and Meseta edifice. Star indicates location of UV camera during field measurements. (inset) UV camera and plume as seen from measurement site. From Nadeau and Dalton (2009).

Figure 13. A map of SO2 concentration-pathlength created from UV imagery of Fuego during the 2009 campaign. Scale bar at bottom indicates concentration pathlength in colored versions (in units of ppm-m with highest values on the scale and in portions of the plume at ~1,000 ppm-m). From Nadeau and Dalton (2009).

Preliminary evaluation of camera-derived emissions at Fuego in January 2009 show decreases in SO2 output prior to explosive events, and may indicate short-term sealing of the vent. Additionally, some small low-frequency seismic events without explosion signals in the acoustic record were associated with short-term increases in SO2 output.

A paper presented by Lyons, Waite, and Rose (2009) suggests the potential to track activity of Fuego volcano using explosive energy partitioning. This has implications for monitoring and hazard prediction.

As previously noted, minor plumes, occasional avalanches, and lahars were reported at Fuego during January 2008-January 2010 (BGVN 34:12). Explosive activity occurred with a similar style from 2002 through December 2010, although the report heights of ash plumes was seldom over 1 km during February to December 2010. As is typical, the bulk of the reporting on Fuego comes from INSIVUMEH (the Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia) and collaborating agencies. The tallest plumes of this interval reached 1.2 km (on 23 December 2010).

This report first presents the February to December 2010 summary, followed by a May 2011 photo. In the next subsection we skip back in time to discuss observations from a visit to Fuego in February 2009. In the final subsection, we note some 2010-2011 studies made at Fuego.

The February to December 2010 information in this report was initially synthesized and edited by Dan Eungard, as part of a graduate student writing assignment in a volcanology class at Oregon State University under the guidance of professor Shan de Silva.

February through December 2010 activity. According to INSIVUMEH, typical activity during February through December 2010 included degassing plumes that rose above the crater punctuated by occasional Strombolian and Vulcanian explosions that produced small ash plumes. These plumes would occasionally rise to 1.2 km above the summit and become large enough for ash to reach local communities, including Alotenángo (8 km ENE), Ciudad Vieja (13.5 km NE), San Miguel Dueñas (10 km NE), Antigua Guatemala (18 km NE), Sangre de Cristo (9.5 km WSW), Yepocapa (9 km WNW), Morelia (11.5 km SW), and Panimache (9 km SW). Major ashfall events occurred on 2-4 March, 10 June, 19 July, 27 August, 13 and 21 September, 28 October, and 22 November 2010 (table 7). Explosions would occasionally generate shockwaves that rattled windows of structures within 15 km of the summit.

Table 7. Summary of activity reported at Fuego during February to December 2010. "--" indicates no reported data. Terms for explosion frequency: Few signifies undisclosed or under 5; Multiple, 5-20; Many, over 20. Information courtesy of INSIVUMEH and Washington Volcanic Ash Advisory Center (VAAC).

Date

Explosions

Ash plume height (m)

Drift

Incandescence (m)

Avalanches

08 Oct 2010

Multiple

600-800

S

100

--

11 Oct 2010

Many

500-800

S-SW

--

--

14 Oct 2010

Many

1000

SW

125

x

18 Oct 2010

Multiple

800

12 km W-S

100

x

22 Oct 2010

Multiple

500-700

SW

weak

x

26 Oct 2010

Many

500

N-NW

75

x

28 Oct 2010

Multiple

400-600

W-NE

75

x

29 Oct 2010

Multiple

300-500

W-SW

75

x

31 Oct 2010

Few

--

20 km W

--

--

5 Nov 2010

Few

900

E

--

--

08 Nov 2010

Few

900

12 km E

100

x

12 Nov 2010

Few

800

S-SW

weak

x

13 Nov 2010

Few

--

37 km SW

--

--

19 Nov 2010

Few

1000

10 km W

100

x

22 Nov 2010

Many

900-1000

15 km SW

--

--

25 Nov 2010

Few

300

W-NW

--

--

04 Dec 2010

Few

--

SW

--

--

06 Dec 2010

Few

900

6 km SW

--

--

08 Dec 2010

Few

500

S-SW

--

x

10 Dec 2010

Few

--

SW

--

--

17 Dec 2010

Few

300-800

E-SE

--

--

20 Dec 2010

Few

500

W-NW

--

--

22 Dec 2010

Few

--

28 km NW

--

--

23 Dec 2010

Many

600-1200

10-15 km SE

--

--

24 Dec 2010

Multiple

400

N

--

--

28 Dec 2010

Few

500

5 km S-SW

weak

x

30 Dec 2010

Many

600-800

8 km W-SW

--

x

Antigua Guatemala, a major tourist location with a local population of ~40,000, has occasionally experienced ashfall from Fuego and Pacaya volcanoes (Pacaya is ~30 km ESE of Fuego). Ashfall was heavy enough to damage infrastructure and collapse roofs in the town of Yepocapa during the 1971 and 1974 eruptions of Fuego. Tephra thicknesses of 300 mm with 50 mm bombs were recorded in the area of Yepocapa during the 1971 eruption, causing 20% of the roofs to collapse "including those of many public buildings" (Bonis and Salazar, 1973). From several case studies, including Fuego, Stromboli, and Deception Island, R.J. Blong (1984) suggests a 100 mm threshold for tephra thickness on roofs. Greater thickness may mean serious structural damage, especially if rainfall accompanies or follows the tephra load.

INSIVUMEH issued civil-aviation alerts several times throughout 2010 due to large ash outputs from Fuego. Washington VAAC released advisories for ash plumes including those that occurred on 31 October; 12-13 November; and 4, 10, and 22 December. Over the course of the year, plume height averaged 530 m above the summit. The plumes drifted laterally up to 37 km from the summit and frequently drifted W, SW, S, and NW.

During the year, local reports and INSIVUMEH observations noted block avalanches within the crater and on the slopes; occasionally they were large enough to reach vegetation. Incandescent pulses were fairly common during Strombolian eruptions and juvenile material reached heights up to 125 m.

Figure 14. The El Jute river channel was a site of major lahar activity at Fuego during tropical storm Agatha in May 2010. This photo was taken 8.7 km SSE from Fuego's summit (seen in the background). The old, dark gray lahar deposits seen here were eroded during the storm leaving this tall 5-m-high scarp. Observers in this 3 May 2011 photo included (from left to right) Marco Antonio Argueta (from the Guatemalan risk group CONRED; Coordinadora Nacional para la Reducción de Desastres), Rosalio Suruy, and Aroldo Surui. Photo by Rüdiger Escobar-Wolf (Michigan Technological University).

February 2009 photos of a minor eruption. During a field campaign, R. Escobar-Wolf visited Fuego and witnessed explosions that emitted a large number of ballistic blocks (not discussed on table 7). On 6 February he photographed the development of a small ash plume as well as a cloud of remobilized ash that rose from the summit area. Figure 15A was taken seconds after the central plume erupted from the summit. Figure 15B shows continued rise of the plume as well as the onset of remobilized ash from the flanks. Figure 15C is a close-up of the central ravine where, after the impact of the ballistic blocks, trails of material fell from the summit.

Figure 15. A sequence of photos (A-C) taken on 6 February 2009, viewing Fuego towards the WNW. See text for more details. Courtesy of Rüdiger Escobar-Wolf (Michigan Technological University).

Escobar-Wolf described this sequence of events as a Vulcanian eruption. The eruption was impulsive and released a central plume that reached ~ 1.5 km above the crater (figure 15B). Around the time of this photo, ballistics appeared to impact the summit and thousands of pale ash clouds rose from the summit's surface. These clouds appeared to spread widely down and along the slope, whereas rising portions dispersed (figure 15C).

Recent publications. Characterization of Fuego's activity and the development of new monitoring techniques have been ongoing for several decades. Three manuscripts were recently published focusing on seismic and gas studies.

Erdem (2010) conducted a geophysical study at Fuego from March to July 2008 using a three-component broadband seismometer and two infrasonic microphones. In order to model temporal changes in eruption dynamics, coda wave interferometry methods were used to analyze a set of highly repetitive seismic events associated with regular discrete degassing explosions. The author found rapid temporal variation in the velocity structure, which may indicate minor fluctuations in volatile content or exsolution at various depths between individual explosions. Variations in seismic and acoustic wave arrival times were used to investigate changes in explosion source depth and wind speed.

Lyons and others (2010) found a cyclic pattern in open-vent eruptive behavior at Fuego based on two years of continuous observations from the Fuego Volcano Observatory made possible by a collaboration between the Peace Corps, Guatemalan scientists, and Michigan Technological University. They found that daily observations of lava flow length and explosion characteristics have a strong correlation with satellite-based remote sensing data and tremor amplitude. The pattern of behavior is interpreted to reflect the slow accumulation and periodic gas release in a foam layer trapped in a relatively deep magma chamber or geometric trap in the conduit. This study highlights the importance of detailed geophysical and field observations as a low-cost option in developing countries, as well as in volcanological training.

Nadeau and others (2011) discuss remote sensing of SO2 emissions using a UV camera. Their analysis of 2009 Fuego data sets assessed SO2 emissions from two closely-spaced vents, compared with both visual observations and seismicity. They concluded that tremor and degassing share a common source process, and they developed a model for small, ash-rich explosions based on evidence for rheological stiffening of magma in the upper conduit. Progressive stiffening may explain why, in time-series data, there is a general increase in time lag between tremor and SO2 escape. This lag may be attributed to a deepening or a reduction in velocity of the gas rise from depth if crystallization and cooling propagates downward through time from the top of the magma column. Different degrees of stiffening and the associated range of confining pressures may cause variability in both degrees of explosivity and durations of inter-explosion quiescent periods.

In this report we highlight Fuego's ongoing eruptive activity during January 2011-March 2013. Elevated activity occurred during May-September 2012 and included regular thermal, gas, and ash emissions with occasional lava fountaining and pyroclastic flows. Activity peaked during 13-14 September 2012 with a VEI 3 (Volcanic Explosivity Index; where 3 is considered moderate (Newhall and Self, 1982)) summit eruption and SW-directed pyroclastic flow.

During this reporting period, continuous monitoring efforts by the Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia (INSIVUMEH) included seismic monitoring, regular ground-based observations, and field visits. The Washington Volcanic Ash Advisory Center (VAAC) regularly included monitoring data from INSIVUMEH with satellite remote sensing emissions announcements. We also summarize a recent international collaboration between INSIVUMEH and the International Volcano Monitoring Fund (IVM-Fund) during 2010-2013.

Local observers reported ashfall, shockwaves, and lahars. According to INSIVUMEH, during 2011-2013, ashfall and explosive sounds were frequently reported by communities located within the W sector and up to 8 km of Fuego's summit. Lahars occurred on the S-sector flank in the Taniluyá, Ceniza, Santa Teresa, Las Lajas, and Trinidad drainages (figure 16). Those drainages were also hazardous due to channelization of pyroclastic flows, block avalanches, and lava flows (figure 17); significant events occurred in mid-to-late 2012 and February 2013 (described later in this report). On the SE flank, Las Lajas was frequently affected by pyroclastic flows, and the drainages Taniluyá and Ceniza (SW flank) occasionally contained active lava flows and block avalanches.

Figure 17. This annotated photograph is centered on Fuego's SW flank, the location of the Ceniza drainage, which channeled the major pyroclastic flow of 13 September 2012. The yellow dotted line marks the centerline of the pyroclastic flow; the orange lines enclose the region burned and scoured by ash cloud surges. Courtesy of INSIVUMEH.

Thermal anomaly detection during 2011-2013. Hotspots from the summit region were detected by satellite remote sensing instruments including MODIS (onboard the Terra and Aqua satellites), Landsat 7, and EO-1 Advanced Land Imaging (ALI) throughout this reporting period.

The MODVOLC thermal alert system recorded ~90 significant anomalies between 1 January 2011 and 1 January 2012, ~375 between 1 January 2012 and 1 January 2013 when explosive activity escalated, and ~255 between 1 January 2013 and 31 March 2013 when lava flows were active near the summit region (figure 18). Thermal anomalies were detected by satellite images at least once per month from January 2011 through March 2013 except for July 2011, suggesting poor weather may have inhibited satellite observations that month (note that heaviest rainfall typically occurs during June-October (The World Bank, 2013)). During July 2011, ground-based observations of nighttime incandescence were noted in INSIVUMEH's Report # 1863; other reports that month highlighted the effects of heavy rain from tropical storms and Hurricane Calvin.

Figure 18. During 1 January 2011-31 March 2013, the MODVOLC system frequently detected elevated temperatures in the area of Fuego's summit. This series of images includes hotspots detected during three time periods: 2011, 2012, and 1 January-31 March 2013. Courtesy of the Hawai`i Institute of Geophysics and Planetology (HIGP), MODVOLC Thermal Alerts System.

MODVOLC continued to detect hotspots during late April 2013 totaling 22 pixels during 21-28 April. Thermal anomalies became rare during May and June 2013; one pixel was detected on three different days.

Regular images captured by ALI and Landsat 7 detected variable incandescence from Fuego's summit during 2011-2013 (figure 19). During 2011, hotspots were mainly located at Fuego's summit; however, during March and December, distinctively elongate, incandescent lava flows extended from the summit to the SW (figure 19A and 19B).

Figure 19. Satellite images from 2011-2013 detected incandescence from Fuego's summit area. (A) This ALI image from 3 February 2011 showed a small region of incandescence isolated at the summit. (B) A Landsat 7 image from 7 November 2011 revealed a ~300 m incandescent flow originating from the summit and extending down the SW flank. (C) This Landsat 7 image from 4 September 2012 (nine days before the VEI 3 eruption began) captures intense incandescence that extends in three directions from the summit; some image distortion is present from cloudcover and artifact stripes (on the left-hand side). Distinctive yellow regions indicate lava reaching at least 500 m SE and SW. (D) This ALI image from 20 March 2013 captures a lava flow extending ~1,500 m SW from the summit crater within the upper region of the Ceniza drainage; some cloudcover blocks the middle region of the lava flow, but the red glow is visible and especially bright at the termination point SW of the clouds. Image processing by Rüdiger Escobar-Wolf (Michigan Technological University); courtesy of NASA/USGS.

Summit incandescence extending SW, SE, and in the immediate summit area was visible during 2012; some of the strongest incandescence extended at least 1 km from the summit to the SW during November-December. Incandescent flows directed SE appeared in April, June, and September. On 4 September 2012, three narrow flows were visible from the summit extending ≥ 500 m from the summit within the S sector; despite significant cloudcover that day and image artifacts, the lava flows were well-defined (figure 19C).

Satellite images from December 2012 through January 2013 included a long lava flow that persisted in the SW drainage (Ceniza), although cloudcover frequently obscured the full view of Fuego's SW quadrant. That incandescent lava flow remained visible in satellite images until late February 2013. Incandescence was isolated at the summit in early March, but on 20 March incandescence re-appeared within the Ceniza drainage and extended ~2,000 m SW of the summit (figure 19D).

Effusive activity during 2011-2013. The style of eruptive activity at Fuego changed near the end of 2010 when lava effusion events started to occur more frequently than explosive eruptions (figure 20). "At a very general level, the more Strombolian eruptions happen typically during lava effusion times and are much smaller than the more Vulcanian eruptions," commented Rüdiger Escobar-Wolf (Michigan Technological University) with respect to Fuego's more than 12 year-long eruption. Continuous unrest (background-level explosions and effusion) was frequently punctuated by short periods of elevated activity during the preceding six years and, during 2012 and 2013, this activity was interrupted by several significant episodes: in 2012, 25-26 May; 10-11 June; 3-4 and 13-14 September; and in 2013, 17-18 February; 3-4 and 19-20 March (figure 19D).

Figure 20. Fuego time series from late 1999 to early 2013 with color codes indicating eruption style (Escobar-Wolf, 2013). Beginning in 1999, the eruption mainly consisted of periods of explosive events (color coded as green) and lava effusion (coded as gray); this constant unrest is considered background activity that has been occasionally interrupted with significant episodes (red lines). This timeline was created and provided by Rüdiger Escobar-Wolf, Michigan Technological University.

The Washington VAAC released an increasing number of notices for the aviation community about volcanic ash throughout 2011- March 2013 (table 8). During 2011, these announcements rarely contained calculated plume altitudes due to poor viewing conditions with satellite remote sensing. Data from INSIVUMEH supplemented these reports with direct observations from Fuego Volcano Observatory, located in Panimaché, 8 km SW of Fuego. On 1 January, 8 January, 23 October, and 24 December 2011, reported plume altitudes were less than 5.2 km a.s.l. and had drift speeds in the range of 2.5-10 m/s, drifting S and SW of Fuego's peak.

Table 8. The Washington VAAC released regular advisories due to emissions from Fuego during 2011-March 2013. Date, time, altitude, drift direction, and reporting sources are included as well as comments that described additional eruption characteristics such as thermal anomalies and weather conditions that may have affected observations. Drift velocities and plume width were also calculated when viewing conditions were optimal. INSIVUMEH was a frequent contributor to these reports; other reporting sources included the satellite GOES-2 (NOAA geostationary weather satellite), MWO (local Meteorological Watch Office), Guatemala City's (MGGT) meteorological reports (METAR), and the global numerical weather prediction models GFS and NAM. Courtesy of Washington VAAC.

Date - Time (UTC)

Altitude (km)

Drift Direction

VAAC Sources

Comments

01 Jan 2011 - 1515

5.2

9 km wide line; W 10 m/s

GOES-13. GFS WINDS.

Several small emissions.

08 Jan 2011 - 1015

5.2

18.5 km wide plume; SW 2.6-5 m/s

GOES-13. GFS WINDS.

Multiple exhalations since 08/0600 UTC; these explosions have been seen in satellite before dissipating.

Small puff seen in visible imagery at 5 km a.s.l. moving SE 3.5 m/s. At 2045 UTC the leading edge was 12 km SE of summit and dispersing. Plume was projected to dissipate within 6 hours.

16 Jan 2012 - 1724

--

--

INSIVUMEH.

The VAAC received information suggesting a possible volcanic ash emission.

16 Jan 2012 - 1740

--

--

GOES-13. GFS WINDS. INSIVUMEH.

INSIVUMEH reported ash to 4.3 km; no ash seen in imagery through 1715 UTC with clear skies.

18 Jan 2012 - 1215

6.7

W at 5-7.5 m/s

GOES-13. GFS WINDS.

Visible and multi-spectral imagery showed a single puff of gas and ash moving W from the summit; ash was projected to dissipate within a few hours as it continued W. A hotspot was detected.

01 Feb 2012 - 1645

--

--

GOES-13. GFS WINDS. INSIVUMEH.

INSIVUMEH reported ash to ~5 km at 01/1600 UTC; ash not observed in satellite imagery even with sparse clouds.

01 Apr 2012 - 1315

5

9.3 km wide line; SW 2.6-5 m/s

GOES-13. GFS WINDS. NAM WINDS.

Plume extended 13 km WSW from the summit; well-defined hotspot seen in imagery; forecast confidence was low based on latest GFS and NAM.

19 May 2012 - 0915

--

--

GOES-13. GFS WINDS. INSIVUMEH.

Ash was not seen in satellite imagery due to darkness; hotspot was visible; INSIVUMEH reported volcanic ash up to 5.5 km a.s.l. to 40 km SW of the summit.

19 May 2012 - 1515

--

--

GOES-13. GFS WINDS. INSIVUMEH SEISMIC DETECTION. INSIVUMEH Photos.

Ash was not seen in satellite imagery due to cloudcover; a strong hotspot was visible in satellite multispectral imagery; seismicity was high.

19 May 2012 - 2045

--

--

GOES-13. GFS WINDS. METAR. INSIVUMEH.

Volcanic ash was not detected in satellite imagery due to extensive cloud cover; INSIVUMEH indicated pyroclastic flows likely and ashfalls have been observed.

20 May 2012 - 0245

--

--

GOES-13. GFS WINDS.

Ash was not observed in satellite imagery due to cloudcover; hotspot had decreased in intensity and late afternoon bulletin indicated decreased energy.

20 May 2012 - 1415

--

--

GOES-13. NAM WINDS. INSIVUMEH.

No ash was observed in imagery although there were thick clouds in the area; INSIVUMEH reported ash emissions up to 3,000 m above the summit moving SW.

20 May 2012 - 1945

--

--

GOES-13. GFS WINDS. INSIVUMEH SEISMIC DETECTION.

No ash was seen in imagery due to cloudcover; seismic signal has almost gone to background but with very occasional bursts that may contain volcanic ash.

21 May 2012 - 0045

--

--

GOES-13. GFS WINDS. INSIVUMEH.

No volcanic ash detected due to cloudcover; INSIVUMEH's evening report only mentioned occasional emission of ash to 4 km a.s.l. or just above the crater drifting SW and dispersed within 9.3 km; seismic activity was back to normal with only occasional small bursts.

25 May 2012 - 1542

--

--;

GOES-13. INSIVUMEH.

Eruption of lava began around 1300 UTC; some volcanic ash was possible.

No plume was seen in satellite imagery due to partly cloudy conditions; pilot report of ash to 7 km a.s.l. moving SW; lava flows generated volcanic ash and gas; no explosive eruption seen in the seismic records; ash was forecasted to moving SW; a strong hotspot was visible in satellite imagery.

26 May 2012 - 0415

--

--

GOES-13. GFS WINDS.

Volcanic ash was not detected in satellite imagery due to extensive cloudcover; INSIVUMEH indicated constant pyroclastic flows and reports of ashfall.

26 May 2012 - 1015

--

--

GOES-13. GFS WINDS. SEISMIC DETECTION.

Volcanic ash was not seen due to darkness and weather conditions; strong hot spot was visible in satellite imagery and seismic activity remained elevated.

26 May 2012 - 1615

--

--

GOES-13. GFS WINDS. INSIVUMEH SEISMIC DETECTION.

Ash was not seen in imagery due to cloud cover; INSIVUMEH indicated that ash and gas emissions continued.

26 May 2012 - 2215

--

--

GOES-13. GFS WINDS. INSIVUMEH SEISMIC DETECTION.

Ash was not seen in satellite imagery due to cloudcover; INSIVUMEH reported decreasing seismicity; a hot spot persisted in multispectral imagery.

27 May 2012 - 0415

--

--

GOES-13. INSIVUMEH.

INSIVUMEH indicated ongoing lava flows; decreasing seismic activity and no mention of ashfall in the most recent report.

05 Jun 2012 - 1732

--

--

GOES-13. INSIVUMEH.

INSIVUMEH reported increasing activity and suggested that an explosive eruption with little or no warning was possible; hot spot was seen in satellite imagery but no volcanic ash due to cloud cover.

06 Jun 2012 - 1729

--

--

GOES-13. INSIVUMEH.

INSIVUMEH reported intermittent explosions expelling ash and gas up to ~600 m above the summit; they warned that an explosive eruption with little or no warning was possible.

07 Jun 2012 - 1715

--

--

GOES-13. INSIVUMEH.

INSIVUMEH reported activity that was limited to within 11 km of the summit; no ash was visible in satellite imagery due to partly cloudy conditions.

11 Jun 2012 - 0945

--

--

Tegucigalpa MWO. GOES-13. GFS WINDS. INSIVUMEH.

No ash seen in satellite imagery due to nighttime darkness; hotspots see for last few hours. INSIVUMEH reported ash to 5 km.

11 Jun 2012 - 1545

--

--

GOES-13. INSIVUMEH.

No ash was seen in imagery although there was some cloudcover; there was a strong hotspot occasionally seen in shortwave imagery; INSIVUMEH reported continuous ash emissions up to 15 km to the W and WNW of volcano.

21 Jun 2012 - 1552

--

--

Tegucigalpa MWO. GOES-13. GEOPHYSICAL INST. EMAILED PHOTOS.

No ash detected due to cloudcover; INSIVUMEH reported ash moving E from rockfalls and aided by heat of lava flows; bit hotspots were visible through clouds.

21 Jun 2012 - 2138

--

--

GOES-13. GFS WINDS.

No ash detected in visible satellite imagery due to cloudcover; hotspot seen in infrared imagery.

22 Jun 2012 - 0340

--

--

GOES-13. GFS WINDS.

No ash seen in visible or multispectral satellite imagery due to night time darkness and cloudcover; hotspot observed prior to clouds moving in 22/0015 UTC.

03 Sep 2012 - 1415

4.3/5.2

5.6 km wide line; SW 5-7.5 m/s7.4 km wide line; W 2.6-5 m/s

GOES-13. GFS WINDS.

Ash plume height confidence is medium, the estimation is based on models and history of volcanic activity; a well-defined hotspot was seen overnight.

03 Sept 2012 - 2015

--

--

GOES-13. GFS WINDS. INSIVUMEH SEISMIC DETECTION.

Due to clouds, no good detection of ash but before the clouds arrived, faint ash was seen W-SW as far as 27.7 km; strong hotspots due to lava flows and rockfalls.

04 Sep 2012 - 0145

--

--

GOES-13. GFS WINDS. INSIVUMEH SEISMIC DETECTION.

No ash detected due to clouds and darkness; multiple hotspots were seen due to rockfalls and lava flows; some ashfall was reported SW of the summit up to 13 km.

04 Sep 2012 - 0445

4.5

W 2.6-5 m/s

GOES-12. GFS WINDS. INSIVUMEH SEISMIC DETECTION.

A plume was visible in multispectral imagery extending about ~145 km W of the summit.

04 Sep 2012 - 1015

4.5

W 2.6-5 m/s

GOES-13.

A continuous emission of ash was visible in multispectral imagery extending ~145 km W of volcano; large hotspot was detected by shortwave imagery.

04 Sep 2012 - 1615

--

--

GOES-13. GFS WINDS. INSIVUMEH.

Ash was not seen due to weather conditions; strong hotspot remains in thermal imagery and INSIVUMEH reported elevated seismic activity.

04 Sep 2012 - 2145

--

--

GOES-13. GFS WINDS. INSIVUMEH SEISMIC DETECTION.

No ash or hotspots detected due to thick clouds; INSIVUMEH reported continued lava flows and rockfalls that generated ash to ~4.5 km a.s.l. moving SW; ashfall was reported up to 15 m SW and W of the summit.

05 Sep 2012 - 1545

--

--

GOES-13. INSIVUMEH.

Ash not seen in the satellite imagery due to partly cloudy skies; a faint hotspot was visible in the morning; INSIVUMEH confirmed that no ash emissions were detected.

Ash plume was 111 km wide and extended 417 W of the summit; ash closest to summit was obscured by cloudcover and was likely rained out; METAR from MGGT continued to report ash.

14 Sep 2012 - 0710

4.3 /7.3

W 5 m/s / W 5 m/s

GOES-13. GFS WINDS. INSIVUMEH.

A bright hotspot persisted with a small plume in multispectral imagery extending 36 km to the W of the summit; latest report indicated current activity was more intermittent and lower in height; larger area to 7.3 km a.s.l. continued to dissipate about 648 km to W of summit moving W.

A dissipating area of ash, about ~1,000 km W of the summit, was detected in multispectral imagery; no ash was seen near the summit at 1845 UTC; INSIVUMEH reported ash emissions within 15 km of the summit.

15 Sep 2012 - 0045

--

--

GOES-13. GFS WINDS. INSIVUMEH SEISMIC DETECTION.

No ash was detected in satellite imagery; the previous plume located S of Mexico had dispersed around 14/2200 UTC. INSIVUMEH reported weaker seismic activity with rockfalls generating ash plumes to 4 km a.s.l. and 15 km W-SW of the summit; a strong hotspot was visible.

INSIVUMEH reports incredible outpouring of lava from the crater which is confirmed by brilliant hot spot in satellite imagery; INSIVUMEH reported no ash plume at the moment, but emissions are possible over the next few hours up to 10 km to the S and SW of the summit.

17 Feb 2013 - 1315

5

W 2.6-5 m/s

Tegucigalpa MWO. GOES-13. GFS WINDS. INSIVUMEH.

In the morning, visible imagery showed a plume of ash extending 18.5 km to the W of the volcano; INSIVUMEH reported ash to 4.8 km a.s.l.

Ongoing emissions of lava with gas and light ash; in imagery the ash is mixed with clouds and, due to light winds spreading N-W-SW from the summit ~13 km; this is mainly a lava event but some light ashfall was being reported in cities on the slopes of the volcano.

18 Feb 2013 - 0815

--

--

GOES-13. GFS WINDS. INSIVUMEH.

Ongoing lava emission with gases and light ash; no ash detected due to large thunderstorm that developed SW of summit and regional cloudcover. INSIVUMEH reported in the afternoon that less energetic lava, gas, and ash events were occurring.

03 Mar 2013 - 2345

--

--

GOES-13. GFS WINDS. INSIVUMEH.

Lava emission with occasional light ash due to rockfalls and small venting; hotspot due to lava but no ash was visible in satellite imagery; plume drifted up to 9 km according to INSIVUMEH; wind forecast was light and variable, so the plume was expected to remain close to the summit region.

04 Mar 2013 - 0334

--

--

GOES-13. GFS WINDS. INSIVUMEH.

An INSIVUMEH special report indicated that a new stage of emissions began and possible ash fall was likely around 18.5 km from the summit. Ash was not seen in multispectral satellite imagery; a very large hotspot was observed with infrared.

04 Mar 2013 - 0845

--

--

GOES-13. GFS WINDS.

Ash was not seen in overnight satellite imagery; very large and bright hotspot was detected with infrared sensors; emissions of gas and ash were likely.

Ongoing emissions; ash was too light to be seen in visible satellite imagery although reports indicate that ash was present; a strong hot spot persisted.

05 Mar 2013 - 0115

--

--

Tegucigalpa MWO. GOES-13.

Ongoing activity; Tegucigalpa MWO canceled Sigmet for the event; a well-defined hotspot was visible in multi-spectral imagery; no ash was present in the last visible images of the day.

18 Mar 2013 - 1345

4.3

moving SW 2.6-5 m/s

Tegucigalpa MWO. GOES-13. GFS WINDS.

Very light volcanic ash emissions; MWO indicated ash moving SW; the ash had a SSW component in satellite imagery and was very light in nature.

18 Mar 2013 - 1945

--

--

GOES-13. GFS WINDS. INSIVUMEH.

Emissions of gas and occasional light ash were near the summit; no ash was detected or reported in cloudy conditions; INSIVUMEH reported near-summit emissions of gas and occasional, very light ash below 4.3 km a.s.l. and within 9 km of the summit.

19 Mar 2013 - 2232

--

--

GOES-13. GFS WINDS. INSIVUMEH.

INSIVUMEH reported ash to 5 km a.s.l. at 19/2045 UTC moving SE at 5 m/s; ash not visible in imagery; special observatory report indicated elevated activity with the volcano; a persistent hotspot was present since 1915 UTC and had become increasingly bright in the past hour.

Near summit emissions of gases and occasional light volcanic ash; although brilliant hot spot was readily apparent in satellite imagery, no ash was detected under partly cloudy conditions.

21 Mar 2013 - 1332

5.5

E 7.5 m/s

GOES-13. GFS WINDS.

Intermittent emissions; ash emissions and a persistent hotspot were observed in satellite imagery in clear skies; several discreet puffs were noted; ash plume extends ~32 km to the ESE of the volcano.

28 Mar 2013 - 1315

4.6

W 2.6 - 5 m/s

GOES-13. INSIVUMEH. ECMWF HIRES WINDS.

Continuous emissions; a series of emissions has resulted in an ash plume extending up to 18.5 km to the WSW of the summit.

30 Mar 2013 - 1415

5

S 8 m/s

GOES-13. GFS WINDS. INSIVUMEH SEISMIC DETECTION.

INSIVUMEH reported degassing with occasional bursts of ash at 1240 UTC, 1330 UTC, and 1415 UTC; multibursts of gas and ash seen moving to S and SE from the summit extending 55.5 km from the summit and dispersing; light ashfall was reported within 18.5 km of the summit.

Ongoing emissions; ash not seen in satellite imagery under clear skies; however, sun may be preventing light ash from being observed; ash had been reported in the village of Panimaché.

31 Mar 2013 - 1945

--

--

GOES-13. GFS WINDS. INSIVUMEH.

Continuous gas emissions with occasional short bursts of light ash; INSIVUMEH reported continued gas emissions with short bursts of light ash moving S; ashfall was reported within 9.3 km of the summit; ash not seen in satellite imagery due to cloud cover around the summit.

During 2011, INSIVUMEH reported that Fuego's activity included small-scale explosions and effusive lava flows. Lava flow activity was reported mainly during late March, late April, June, and early July. The longest lava flows traveled SW within the Ceniza and Santa Teresa drainages. Maximum flow lengths were in the range of 100-200 m and were frequently incandescent at night during spalling events.

Escalating summit activity during 2012. In early 2012, three VAAC advisories included plume altitudes as high as 6.7 km a.s.l. and drift directions up to 7.5 m/s S, SW, and W (table 8). INSIVUMEH reported that during the first week of January 2012, the Alert Level was raised to Yellow due to elevated activity; incandescent explosions were observed during 18-19 and 23 January. Lava flows and intermittent incandescent spatter continued from the summit throughout the rest of this reporting period (2011-March 2013).

The Coordinadora Nacional para la Reducción de Desastres (CONRED) announced Alert Level Orange (third highest on a four-color scale) and evacuations from El Porvenir in Alotenango (9 km ENE) on 19 May due to escalating activity (figure 21). Energetic Strombolian eruptions occurred during 19-20 and 25-27 May. Pyroclastic flows during 25-26 May were directed E and SE (impacting the Las Lajas and El Jute drainages), unlike previous events that concentrated flows within the W sector. Significant populations, resorts, and infrastructure such as the RN-14 road are located along the Las Lajas and El Jute drainages.

Figure 21. A plot of the daily average RSAM (Real-time Seismic-Amplitude Measurement) from Fuego's seismic station FG3 during January through September 2012. Notable peaks include eruptions during 19-20, 26-27 May and 11 June; the effusive eruption of 1 July; the 3 September eruption, lahars, and lava flows; and the 13 September eruption. During this time period, seismicity was dominated by long-period (LP) earthquakes generated by processes such as explosions, fluid movement, lava flows, and block avalanches. Courtesy of INSIVUMEH.

During May-June, there were ~20 VAAC advisories that highlighted INSIVUMEH observations and the possibility of ash plumes; satellite observations and calculations of plume altitudes, however, were not available (table 8). INSIVUMEH reported lava flows throughout May-August (extending up to 1.7 km from the summit and as wide as 25 m) and pyroclastic flows occurred during May.

Increased explosivity at Fuego during September 2012. During the first week of September 2012, the Washington VAAC issued advisories describing ash plumes up to 5.2 km a.s.l. (table 8). A large event, on 3 September, generated two ash plumes dispersing SW and W, the former was ~5.5 km wide, and the latter was ~7.5 km wide. Ash plumes and hot spots continued to be visible within satellite images through 4 September (figure 19C) with INSIVUMEH reporting a lack of ash clouds on 5 September, followed by a break in reports until the major eruption on 13 September.

Beginning at 0400 on 13 September, a significant eruption occurred which led to evacuations from local communities within a 10-km radius (figures 22 and 23). At 0715, a vertical plume erupted from the summit. Large pyroclastic flows were generated between 0900 and 1000 local time which became channelized within two drainages. Within the Las Lajas drainage (on the SE flank), flows reached as far as 2 km from the summit; within the Ceniza drainage (SSW flank), they traveled as far as 7.7 km, stopping just 3 km short of Panimaché. On 14 September, the Washington VAAC reported ash plumes up to 7.3 km a.s.l. that drifted W at ~10 m/s (table 8).

Figure 22. On 13 September 2012, a large plume of ash erupted from Fuego and pyroclastic flows descended the flanks. Between 0900 and 1000 local time, a lateral cloud and a tall plume expanded from the summit. The sharp peak to the right of Fuego is Agua volcano. This photo was taken from a viewpoint near the base of Pacaya volcano, ~30 km S of Guatemala City. Photo courtesy of Kent Caldwell.

Figure 23. Comparison views of Fuego made from the city of Antigua (~18 km from Fuego) looking SW. (Top) This view from the center of Antigua, was taken on 21 March 2008 at 0915 when volcanic unrest was dominated by intermittent, impulsive eruptions which generated short gas-and-ash plumes (see figure 20 for the timeline of explosive vs. effusive activity). Photo courtesy of Kyle Brill (Michigan Technological University). (Bottom) This photo taken at ~0900 on 13 September 2012 captures a view SW of the ongoing explosive eruption that continued through 14 September. Photo courtesy of Luis Echeverria (Xinhua Press/Corbis).

In a special report by INSIVUMEH, the 13-14 September 2013 eruption was described as the largest explosive event within the last 13 years; they assigned the event VEI 3 (Volcanic Explosivity Index) based on the volume of pyroclastic material. This was the first eruption since 1974 that directly impacted the S and SW zones of Fuego, areas within 5-7 km of the summit that contained numerous small villages (figure 24). Approximately 10,600 people were evacuated from Panimaché I, Panimaché II, Sangre de Cristo, Morelia, and El Porvenir (figure 16) to the town of Santa Lucía Cotzumalguapa (18 km SW). INSIVUMEH estimated that ~5 mm of ashfall accumulated in those regions closest to the channelized pyroclastic flows. Ashfall damaged coffee and other agricultural crops in the region and congested the air, decreasing visibility in many communities within 10 km of the summit.

Figure 24. Two hybrid graphics each merging a regional map and MODIS image centered on Fuego (at the red pushpin icon). (A) Results captured at 1030 local time showing a plume generated by the eruption covered approximately ~900 km2. (B) At 1330 local time, the ash plume covered approximately ~2,500 km2, with less density; 47 municipalities in seven departments were primarily affected. The ash extends off this graphic and later reached Chiapas, Mexico. Image modified from CATHALAC, 2012.

Prior to the eruption, there wsa a notable increase in LP seismicity and high-amplitude tremor that lasted for hours. INSIVUMEH seismic records became saturated between 0947 and 0949, the time period when observers noted ash plumes rising from the summit (figure 7). During the explosive event that began at 0400 on 13 September 2012, a lava flow advanced 300 m down the flank from the S side of the summit crater. At roughly the same time, a vertical plume rose from the crater and drifted SW; strong ENE winds rapidly spread the ash into the coastal Suchitepéquez Department. At 0715 the ash plume had risen up to 2 km above the summit crater; by 1500 that day, a diffuse ash plume was reported over the S region Mexico's Chiapas Province. The ash continued to expand W and NW on 14 September, and was ~100 km wide and more than 415 km W of the summit (table 8 and figure 10); ash persisted in the atmosphere for more than 36 hours.

Figure 25. A large ash plume drifted W and NW from Fuego on 14 September 2012; observations were made at 0045, 0700; 1300; and 1900 local time and remote sensing measurements determined an altitude of ~7 km a.s.l. These graphics notified the aviation community about airspace containing ash plumes. Note that "VA to FL 240" means "volcanic ash to flight level 24,000 (~7 km)." Courtesy of Washington VAAC.

Seismicity and surface activity returned to low levels after the powerful 13-14 September 2012 eruption. Field studies conducted by INSIVUMEH determined that the Las Lajas, El Jute, Trinidad, and Ceniza drainages received the largest concentration of volcanic material during the eruption, making these regions susceptible to lahars with the onset of the rainy season.

Within the Ceniza drainage, in particular, pyroclastic flows had extended ~8 km (figures 17 and 26) and had deposited tree branches and trunks (many that were charred) within the canyon along with large (1-3 m diameter) blocks and volcanic bombs. Preliminary assessments of the deposits within the Ceniza drainage determined that ~13,000,000 m3 of material had been deposited and was already becoming mobilized.

Figure 26. During field investigations immediately after the 13 September 2012 eruption, INSIVUMEH surveyed the Ceniza drainage to assess both the damage and potential new hazards from lahars. This area sits in the region of Siquinala and San Andrés Osuna, ~13 km SSW of Fuego's summit. Courtesy of INSIVUMEH.

Assessments by INSIVUMEH at the end of 2012 determined that two months of heavy rain had cut deep incisions into the new deposits and that loose, fine-grained volcaniclastic material had already migrated down to the road crossing at Siquinala and San Andrés Osuna, ~13 km SSW of the summit. The study also described the increased vulnerability of the road access for Siquinala and the community of La Róchela (figure 16) due to possible stream capture by Ceniza with Platanares. A narrow (~15 m) zone of the Ceniza drainage had been filled with volcaniclastic material, changing the drainage profile in a location ~2 km upstream from an important stream crossing. The Ceniza drainage had been migrating laterally toward the Platanares over time, especially due to erosion following Tropical Storm Agatha in 2010.

Explosive and effusive activity continued during September 2012-March 2013.From late September 2012 through March 2013, INSIVUMEH documented ash plumes (100-1,300 m above the crater), incandescent spatter (50-200 m above the crater), lava flows (mainly flowing 100-900 m down the SW flank), and lahars. In 2012, hot lahars were reported on 1 June, and later on 27 September and 3 October. Lava flows were frequently channelized within the Ceniza, Trinidad, and Taniluya drainages (SW flank). The last significant VAAC report of 2012 highlighted discreet puffs of ash that reached a maximum of 900 m above the crater on 29 September (table 8).

Large pyroclastic flows on 16 and 17 February 2013 traveled 3 km down the Ceniza drainage (table 8). Ash plumes generated on 16 February caused ashfall in communities up to 12 km from the summit, primarily SW. On 17 February there were collapses at lava-flow fronts.

On 4 March 2013 there were large lava flows following incandescent explosions up to 100 m above the crater (table 8).

On 19 March an explosive eruption occurred with effusive lava flows; a ~5 km a.s.l. ash plume was detected by the Washington VAAC (table 8). Lava fountaining reported on 20 March rose 300-400 above the crater; a ~1.5 km long lava flow within the Ceniza drainage was also observed that day (figure 19D). Incandescent explosions were frequently observed through the rest of the month.

International collaboration aids monitoring capabilities in 2013. In 2010, a partnership was established between INSIVUMEH observatories and the International Volcano Monitoring Fund (IVM-Fund), a non-profit organization based in Seattle, WA. After a successful project to improve monitoring efforts at the Santiaguito Volcano Observatory (OVSAN), the IVM-Fund began working with the Fuego Volcano Observatory (OVFGO), located in Panimaché, in 2012. During March 2013, this observatory received significant support from the IVM-Fund and international donors. Jeff Witter, president and CEO of the IVM-Fund, delivered ~$4,500 worth of field equipment to OVFGO to help outfit the observers and contribute to volcano monitoring capacity in Guatemala (figure 27). Additional visits to Guatemala are planned once sufficient funds are raised to continue the IVM-Fund's collaborative work with Guatemalan volcanologists. Volcano monitoring support projects between the IVM-Fund and INSIVUMEH are planned to address additional needs at OVFGO and OVSAN.

Figure 27. On 21 March 2013, INSIVUMEH technician Amilcar Cardenas (left) and Edgar Barrios (far side of river) measure the width of Taniluya drainage to collect baseline data for monitoring geomorphologic changes in the canyon. This drainage is particularly susceptible to lahars and pyroclastic flows. Courtesy of Jeff Witter (IVM-Fund).

References. CATHALAC, 2012, "Preliminary Analysis of the Eruption of Volcan de Fuego, Guatemala -- 13 September 2012," posted on 27 September 2012, https://servirglobal.net/Global/Articles/tabid/86/Article/1169/preliminary-analysis-of-the-eruption-of-volcan-de-fuego-guatemala-13-september.aspx, accessed on 17 July 2013.

In this report we highlight Fuego's ongoing eruptive activity during April 2013-June 2014. During this reporting period continued monitoring by the Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia (INSIVUMEH) included ground-based observations, field visits, and seismic monitoring. Aviation reports were abundant from the Washington Volcanic Ash Advisory Center (VAAC). The active summit crater was a frequent source of thermal alerts from the MODVOLC system which is based on infrared radiation detected in space by the MODIS instruments.

Advancing lava flows and ash explosions. INSIVUMEH reported that lava flows advanced from Fuego's summit during the entire reporting interval. By 29 June 2014, a lava flow was extending 150 m toward the TaniluyÁ drainage and generating avalanches that reached the Ceniza drainage. Earlier in the year, lava flows up to 550 m long reached vegetated areas on the SW flank.

Figure 28. Two satellite images captured incandescence from Fuego on 18 January 2014 (top) and 4 December 2013 (bottom). (top) This EO-1 ALI image is the product of 3 bands: band 10 for thermal, band 9 for clouds, and band 4 for near-infrared. A small, round ash plume was also visible drifting NE of the summit. (bottom) This Landsat 8 image is a combination of visible and infrared bands (band 7 for near-infrared, band 6 for thermal infrared, and band 3 for chlorophyll absorption). Image processed by Rüdiger Escobar Wolf (Michigan Tech University) and acquired by NASA/USGS.

Figure 29. Comparisons of infrared video images with seismic traces for Fuego during 21-22 April 2014. These still views (A-C) enabled viewers to gauge the degree, timing, and correlation between major explosions accompanied by incandescence and seismic signals. The respective images coincide with the points along the seismic trace intersected with the heavy black vertical lines. Courtesy of Rüdiger Escobar Wolf (https://www.youtube.com/watch?v=mvGw7AUCtCo), INSIVUMEH, US-AID, and Michigan Tech University.

Figure 29 shows moderate-sized (~200-m-high) incandescent plumes occurring at the time of high-amplitude seismic signals (panels A and B) whereas minor explosions (panel C) produced little-to-no seismic signal (note that no significant seismicity occurred near the 10:20 tickmark). The Michigan Tech research team postulated that the lack of seismic signal in panel C is the result of the seismometer only registering the ground coupled airwaves during the sequence as opposed to the explosion signature (personal communication by Rüdiger Escobar-Wolf). Some of the explosions recorded during this time were heard in neighboring communities.

Shockwaves from explosions, rumbling from avalanches, and ashfall from explosive events were frequently reported by inhabitants from local communities (table 9). Windows and metal roofs rattled during major events and there were such numerous reports received by INSIVUMEH from residents within 10 km of the summit.

Table 9. Ashfall from explosions at Fuego was reported in numerous communities during 27 March 2013 - 19 June 2014. A map of town locations can be found in BGVN 36:06, figure 16. Courtesy of INSIVUMEH.

Thermal anomaly detection during 2013-2014. Except for June 2014, hotspots at the summit region were detected by satellite remote sensing instruments during each month of this reporting period (table 10). Platforms capturing the infrared data included MODIS (onboard the Terra and Aqua satellites), Landsat 8, and EO-1 Advanced Land Imaging (ALI).

Table 10. The MODVOLC system generated thermal alerts from Fuego during April 2013-May 2014. Courtesy of HIGP.

Month

Pixels

14 Apr 2013

2

21 Apr 2013

1

23 Apr 2013

1

25 Apr 2013

2

26 Apr 2013

3

27 Apr 2013

4

28 Apr 2013

9

09 May 2013

1

15 Jun 2013

1

17 Jun 2013

1

08 Jul 2013

2

10 Jul 2013

2

12 Jul 2013

1

15 Jul 2013

1

22 Jul 2013

2

26 Jul 2013

1

28 Jul 2013

2

29 Jul 2013

1

08 Aug 2013

1

09 Aug 2013

1

11 Aug 2013

1

15 Aug 2013

2

18 Aug 2013

2

19 Aug 2013

1

20 Aug 2013

4

23 Aug 2013

1

03 Sep 2013

1

14 Sep 2013

1

05 Oct 2013

1

11 Oct 2013

2

14 Oct 2013

2

04 Nov 2013

4

15 Nov 2013

1

18 Nov 2013

1

19 Nov 2013

3

20 Nov 2013

2

24 Nov 2013

2

27 Nov 2013

1

03 Dec 2013

1

05 Dec 2013

1

10 Dec 2013

2

15 Dec 2013

5

16 Dec 2013

2

28 Dec 2013

2

30 Dec 2013

1

02 Jan 2014

1

05 Jan 2014

1

07 Jan 2014

4

11 Jan 2014

1

15 Jan 2014

2

18 Jan 2014

5

20 Jan 2014

1

22 Jan 2014

1

23 Jan 2014

2

25 Jan 2014

5

28 Jan 2014

1

29 Jan 2014

2

31 Jan 2014

1

02 Feb 2014

1

04 Feb 2014

1

05 Feb 2014

5

06 Feb 2014

1

07 Feb 2014

1

08 Feb 2014

1

12 Feb 2014

1

21 Feb 2014

2

24 Feb 2014

1

01 Mar 2014

1

05 Mar 2014

1

11 Mar 2014

3

20 Mar 2014

1

21 Mar 2014

1

23 Mar 2014

4

25 Mar 2014

2

27 Mar 2014

1

28 Mar 2014

1

29 Mar 2014

1

30 Mar 2014

2

01 Apr 2014

1

15 Apr 2014

1

16 Apr 2014

1

21 Apr 2014

1

22 Apr 2014

1

27 Apr 2014

1

17 May 2014

1

18 May 2014

2

19 May 2014

2

Lahar hazards. Drainages within the southern sector of Fuego were frequently at risk for lahars during 2013-2014. In particular, the rivers Las Lajas, El Jute, Honda, Seca, Ceniza, Santa Teresa, and TaniluyÁ were inundated by lahars during this reporting period (table 11). A map of river locations can be found in figure 7 of BGVN 30:08.

Table 11. During May 2013-June 2014, weak- to strong-flowing lahars from Fuego were frequently triggered by heavy rainfall, mainly during May-September (the rainy season) each year. Courtesy of INSIVUMEH.

Volcán de Fuego, one of three active volcanos in Guatemala, has been erupting continuously since 2002. Historical observations of eruptions date back to 1531, and radiocarbon dates are confirmed back to 1580 BCE. These eruptions have resulted in major ashfalls, pyroclastic flows, lava flows, and damaging lahars. A major explosion on 13 September 2012 that caused significant ashfall to the S and SW (figure 30) was described by the Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia (INSIVUMEH) as the largest event in the prior 13 years. From September 2012 through June 2014 continuing explosions with ash plumes and ashfall, pyroclastic flows, lahars, and lava flows have impacted much of the region within 20 km of the volcano (BGVN 39:04). This report covers the ongoing activity from June 2014 through mid-December 2015. In addition to regular reports from INSIVUMEH, information comes from the Coordinadora Nacional para la Reducción de Desastres (CONRED), and aviation alerts are provided by the Washington Volcanic Ash Advisory Center (VAAC).

Figure 30. Guatemala's Volcán de Fuego (Volcano of Fire) erupted on the morning of 13 September 2012. According to the Coordinadora Nacional para la Reducción de Desastres (CONRED), the eruption included ash emissions to the W and a 500-m-long lava flow. This natural-color image was acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Terra satellite. Courtesy of NASA-Earth Observatory.

Fuego was continuously active from June 2014 through December 2015. Ash plumes generally rose to heights of less than 1 km above the summit (4.8 km altitude) and dispersed ash over villages located 10-15 km S, SW, and W virtually every week, and occasionally to the NE and E. The highest plumes rose to 5.75 km in October 2014, 5.8 km in January 2015, and at least 6.1 km in February 2015. The most significant ash eruptions were in February 2015 when air traffic was disrupted in Guatemala City and in November 2015 when ashfall was reported up to 90 km SW. Incandescent ejecta rose 100-300 m above the crater rim on a regular basis, but the strongest events sent tephra and lava fountains as high as 500 m in July 2014, 800 m in August 2014, and 500 m in December 2015. Pyroclastic flows descended several drainages during larger explosive events in February, July, September, and November 2015. Numerous lava flows affected at least five different drainages around Fuego. They were reported during June, July, and August 2014, and February-April, June, and September-November 2015. Lahars during June and September 2014 and June 2015 damaged roadways and filled ravines with meter-sized debris. Table 12 shows the towns and drainages mentioned in the report and their distances and directions from the summit of Fuego, and is posted at the end of this report.

Activity during June-December 2014. Activity at Fuego during June 2014 was dominated by explosions that produced ash plumes which rose between 100 and 800 m above the summit (3.9-4.6 km altitude), and drifted most often generally westward. Minor amounts of ash were reported from explosions on 18-19 June in towns within 15 km of the summit, mainly El Porvenir (8 km ENE), Los Yucales (12 km SW), Santa Sofía (12 km SW), Morelia (10 km SW), Sangre de Cristo (10 km SW), and Panimaché (I and II, ~8 km SW). The Washington VAAC issued three reports of minor volcanic ash from explosions on 18, 20, and 23 June, which dissipated within a few hours.

Numerous lahars impacted drainages in June. Las Lajas (SE), Honda (E), and Seca (W) drainages were affected on 1 June, and Las Lajas and El Jute (SE) were impacted the next day. Honda, El Jute, Ceniza (SSW), and Santa Teresa (S) drainages had 1.5-m-diameter blocks in lahars on 5 June, and there were more lahars in Las Lajas and El Jute drainages on 9 June. Incandescent ejecta rose 100-200 m above the crater rim several times, and was responsible for avalanches descending the Taniluyá (SW), Trinidad (S), and Ceniza drainages. A new lava flow reported on 29 June descended the Taniluyá drainage for 150 m and caused avalanches in the nearby Ceniza drainage.

Surges of lava and incandescent avalanches traveled down six drainages (Santa Teresa, Taniluya, Ceniza, Trinidad, Las Lajas, and Honda) during the first half of July 2014, the farthest going 400 m down the Ceniza. MODVOLC thermal alerts possibly related to the lava flows and incandescent material were captured on 1, 2, and 11 July. Pulses of incandescent material rose to 100 m above the rim in early July, but increased to heights up to 500 m above the crater for the second half of the month, causing block avalanches down the flanks. Weak-to-moderate ash-bearing explosions early in the month increased to moderate-to-strong explosions by month's end that sent dark gray ash 400-600 m above the crater. The Washington VAAC reported ash plumes on 8, 11, 18, and 31 July. While no emissions were reported on 11 July, strong winds scattered recent ash as high as 5.5 km altitude (1.8 km above the crater). Ashfall was reported most days in nearby areas, including the Santa Teresa, Taniluya, Ceniza, and Trinidad drainages, and at the Observatory, Morelia, Santa Sophia, Ingenio los Tarros (15 km SW), Panimaché, Yepocapa (9 km NW), and Finca La Conchita.

During August 2014, explosions with incandescent blocks rose 50-400 m above the crater, but explosions as high as 800 m occurred several times. Block avalanches traveled down the flanks into Taniluya, Ceniza, Las Lajas, Trinidad, Honda, and Santa Teresa canyons. Ash plumes rose 300-900 m above the crater and drifted in various directions as far as 15 km before dissipating, numerous times during the month. The Washington VAAC reported a number of discrete ash emissions during 5-8 August, although most were not visible in satellite imagery, and again on 18 August when the highest plume of the month was reported at 5.5 km, or 1.7 km above the crater moving NW. Ashfall was reported in the villages of Yepocapa, Finca La Conchita, Sangre de Cristo, Morelia, and Panimaché I and II, Santa Sofia, Alotenango (8 km ENE), Antigua (18 km NE), San Miguel Dueñas (10 km NE), and around the Observatory. On 30-31 August lava flowed again towards Ceniza Canyon.

On 2 September 2014, INSIVUMEH seismically detected a lahar flowing through the Taniluyá drainage which was measured at a width of 75 m and a height of 2.5 m. The flow cut the road between Santa Lucia Cotzulmaguapa and the communities of Morelia, Santa Sofía, and Panimaché I and II. Lahars were also detected within Río Ceniza and Santa Teresa drainages. Incandescent blocks rose 75-100 m above the crater and weak avalanches were channeled into the Ceniza, Trinidad, Taniluyá, Santa Teresa, Las Lajas, and Honda drainages. Ash plumes rose 500-1,000 m above the summit crater and drifted a few tens of kilometers before dissipating. Fine gray ashfall was reported in communities within 10 km SW and ENE. A lava flow in Ceniza Canyon was 100 m long by 13 September. During 16 September, ashfall was reported in the communities of Alotenango, Antigua, and Ciudad Vieja (13.5 km NE), up to around 20 km NE. Another lahar was detected on 22 September, flowing down the El Jute and Las Lajas drainages on the SE flank carrying volcanic debris, lava blocks, branches, and tree trunks.

This moderate activity continued into early October 2014. Ash plumes that rose to 1,950 m above the summit (5.75 km altitude) were reported by INSIVUMEH during 11-12 October, and plumes to 5.5 km were reported by the Washington VAAC on 28 October. MODVOLC thermal alerts were issued during 5-6-7 October and 23-24 October.

Activity increased again in November 2014. Larger explosions generated block avalanches that descended the drainages on the SE and SW flanks, and ashfall was reported numerous times in the villages within 15 km SW. The Washington VAAC issued 5 series of alerts during 10-11 (drifting NE at 5.2 km), 13 (drifting S), and 17, 23, and 28-29 November (drifting 25 km W at 4.6 to 4.9 km altitude). MODVOLC thermal alerts were also issued on 7 days, including 3 pixels on 25 November.

Heightened activity continued into December 2014 with Special Bulletins issued by INSIVUMEH on 1 and 10 December noting more frequent and intense explosions (as many as 6-8 per hour), and dense gray ash plumes drifting 20 km W and SW depositing fine ash. Lava fountaining was reported on 10 December rising 100-150 m above the crater. The Washington VAAC reported ash plumes on 1-2, 5, 12-15 (S, SE), 27 (NW), and 29-30 (W) December based largely on reports from INSIVUMEH. The plume heights ranged from 4.1 to 4.9 km altitude (300-1,100 m above the crater). There were also MODVOLC thermal alerts on 9 days during December, including three pixels on 6 December.

Activity during 2015. Similar activity continued into January 2015. Ashfall was reported 10-15 km SW from plumes rising 550-950 m above the crater. Incandescent blocks traveled down the SW and SE drainages, generating small fires in vegetated areas. MODVOLC thermal alerts were issued on eight different days during January. The Washington VAAC only issued reports on 9 and 12 January. The 12 January plume was reported as discrete volcanic ash emissions seen in visible satellite imagery fanning out about 16 km W of the summit. The altitude of the plume was noted as 5.8 km, or 2 km above the summit.

A significant Strombolian eruption began on 7 February 2015 that lasted for about 22 hours; pyroclastic flows also descended multiple drainages (figure 31). CONRED reported that ash fell in Guatemala City (about 40 km ENE) and flights were diverted to El Salvador. The communities that reported ashfall from the event are shown in figure 32. The Washington VAAC reported an ash plume visible at about 6.1 km altitude (2.3 km above) and 45 km E of the summit. The next day, the plume was still visible at 5.8 km altitude about 100 km E.

Figure 31. An ash cloud from a pyroclastic flow at Fuego on 7 February 2015 fills the horizon. Courtesy of INSIVUMEH and CONRED.

On 8 February, although activity had decreased, the seismic network detected 30 explosions per minute. The explosions generated shock waves detected in areas 15 km S and SW. Lava flows up to 2 km long were observed in the El Jute and Trinidad drainages on the SE flanks, reaching vegetated areas and causing fires. Sixteen MODVOLC thermal alert pixels were recorded on 8 February; they continued on 9, 11-13 and 17 February before a 10 day break. INSIVUMEH noted that by 9 February activity levels had subsided with weak to moderate explosions producing ash plumes that rose 550 m above the summit and drifted 8-10 km NW (figure 33).

More intense activity returned on 16 February with 4-6 ash-bearing explosions per hour. The Washington VAAC reported the plumes at 4.9 km altitude, although INSIVUMEH noted pilot reports of ash at 7-9 km altitude. Ash fell in many villages to the NW, W, S, and SE more than 15 km from the summit. By 19 February, the ash plumes extended up to 150 km S of the summit. Intermittent emissions with dense ash plumes continued to rise from Fuego and disperse through 22 February.

A new effusive episode began on 28 February 2015 when lava fountains rose 300-400 m above the summit. A strong MODVOLC thermal alert signal persisted with multiple pixels through 3 March; afterwards MODVOLC pixels only appeared on six additional days during the month. One lava flow traveled 1.6 km S down the Trinidad drainage and another traveled 600 m W down the Santa Teresa drainage. Ash plumes also rose up to 1.25 km above the crater and drifted 35 km W generating ashfall in communities to the SW. Numerous ash plumes continued intermittently; VAAC reports were issued on 16 days during the month, through 24 March.

Hot spots appeared in satellite data numerous times during April 2015. Incandescent tephra was ejected 150-200 m above the crater. Block avalanches continued from the end of a new 300-m-long lava flow in the Trinidad drainage on 17 April. MODVOLC thermal alert pixels appeared on 12 days through 26 April, with large multi-pixel alerts on 17 and 18 April. According to INSIVUMEH, ash plumes continued rising 650-850 m above the crater and drifting 8-11 km S, SW, and W, but VAAC reports of ash only appeared on 17 and 18 April.

Far fewer MODVOLC thermal alerts were issued during only five different days spanning 5-31 May 2015. The Washington VAAC issued reports of ash plumes on 13, 15, 17, and 18 May. INSIVUMEH noted an increased number and intensity of explosions briefly during 14-15 May; ash plumes rose 450-750 m above the crater and drifted 10-12 km W and SW. They also reported a S-flank lava flow on 18 May. Ashfall was reported in the communities within 10 km SW of the summit. Incandescent material was ejected 150-200 m above the crater, causing block avalanches in drainages on the S and SW.

Strombolian activity again increased during June 2015, ejecting material 300 m above the crater for 30 hours during 4-6 June. Ash plumes rose to around 1 km above the summit and drifted 10-15 km S and SW. During this episode, lava flows traveled 600 and 1,200 m down the Santa Teresa and Trinidad drainages. Two cinder cones within the crater were reported on 6 June. A lahar was detected on 12 June that was 25 m wide and 2-3 m deep, travelling S down the Trinidad drainage carrying abundant volcanic material and blocks 1-2 m in diameter. MODVOLC thermal alerts were captured on 16 days during June. The Washington VAAC reported ash plumes from explosions on 5, 6, and 28 June with altitudes below 4.8 km and ashfall within 10 km in many areas, including La Soledad (11 km N) and Acatenango (12 km NW). During 29-30 June a 300-m-long lava flow was visible in the Las Lajas drainage on the SE flank.

Based on INSIVUMEH notices, CONRED reported that for a 30-hour period during 30 June-1 July 2015 activity at Fuego was at a high level, characterized by explosions, high-temperature pyroclastic flows (that began on 1 July), and ashfall. Ash plumes rose 4.8 km above the crater and drifted 25 km W and NW, producing ashfall in 22 local communities. An SO2 plume drifting NW was captured by the OMI instrument on the Aura satellite on 1 July (figure 34). The majority of material deposited by pyroclastic flows was located in the Las Lajas drainage where the flow reached 4-5 km in length. People in the La Reunion area near the river bed were evacuated. Nine MODVOLC thermal alert pixels were captured on 1 July, and 10 on 2 July, corroborating the high-temperature pyroclastic flows reported by CONRED. Only single thermal alert pixels were captured after that on 14, 25, and 29 July. The Washington VAAC reports issued on 1, 2, 6, and 14 July included reports of ash emissions to 4.9 km extending up to 55 km SW.

Figure 34. An SO2 plume drifting W from Fuego on 1 July 2015 during a phase of high eruptive activity. Courtesy of NASA GSFC.

Although there were no VAAC reports issued between 14 July and 1 September 2015, the number of MODVOLC thermal alerts increased substantially during August from the previous month, with an especially large multi-pixel signature from 5 through 10 August. INSIVUMEH reported ash plumes rising to 4.2-4.6 m dispersing ash around 12 km in various directions several times during the month, as well as incandescent material rising to 200 m above the crater and sending block avalanches down the drainages on the S and W flanks.

Lava fountains, explosions, pyroclastic flows, and ashfall in surrounding areas picked up again beginning with a strong MODVOLC thermal alert signal on 30 August and lasted through 2 September. By the time activity decreased that day, the remnants of three lava flows were visible in the Santa Teresa, Trinidad and Las Lajas drainages on the S and SE flanks. There were no MODVOLC thermal alerts between 2 and 27 September, and no Washington VAAC reports between 2 and 29 September. During this time, INSIVUMEH reported moderate levels of explosions with ash-bearing plumes rising to 4.5 km altitude and drifting 10-12 km from the summit, dispersing minor amounts of ash to the villages within that radius.

The next pulse of activity began with three MODVOLC thermal alert pixels on 27 September 2015. Lava flows were persistent during October, as reported by INSIVUMEH and evidenced by the number of MODVOLC thermal alert pixels. Multi-pixels days were common between 27 September and 14 October, and again from 23-28 October. INSIVUMEH first reported lava flows on 4 October that were 400 m long in the Santa Teresa drainage and 300 m long in the Trinidad canyon. By 8 October the Trinidad canyon flow was 1.5 km long; the Santa Teresa canyon flow reached 1 km from the crater by 13 October. These flows were fed by Strombolian activity that had increased on 10 October, sending incandescent material 200 m above the crater (figure 35). Lava fountains during 13-14 October produced another lava flow in the Santa Teresa canyon that was 500 m long by 20 October.

Figure 35. Lava flows in the Santa Teresa drainage at Fuego fed by Strombolian activity from the summit vents, 10 October 2015. View is from Yepocapa, 8 km NW. Courtesy of INSIVUMEH (http://www.insivumeh.gob.gt/erupcion_volcan_fuego.html)

A new surge of activity beginning on 21 October through the end of the month generated 200-300 m-high lava fountains that advanced lava flows 1.5 km down the Santa Teresa, Trinidad, and Las Lajas drainages. Ash plumes during October reported by INSIVUMEH rose 450-1,200 m above the crater, dispersing ash to villages 10-12 km S and SW on several occasions; no ash plumes were observed by the Washington VAAC until 26 October when a plume rose to 5.2 km (1.4 km above the summit) and drifted SW.

On 1 November, the Washington VAAC reported discrete ash emissions at 5.2 km altitude drifting SW that dissipated within 50 km early in the day, and a second slightly higher plume later in the day that also dissipated quickly. Most of the rest of the ash plumes at the beginning of November were under 1 km in height above the summit and dispersed ash to communities within 12 km SW. Block avalanches from a 200-m-high fountain of incandescent ejecta traveled down Santa Teresa, Trinidad, and Las Lajas drainages early in the month.

New lava flows were reported in the Las Lajas and El Jute drainages beginning on 9 November 2015. A strong multipixel MODVOLC signal was captured during 7-11 November, including 12 pixels on 9 November. By 10 November the lava flows were 2.5 km long, and incandescent material was ejected 300 m high. Ashfall was reported in Panimache I and II, Morelia, Santa Sofia, El Porvenir, Sangre de Cristo and the municipality of San Pedro Yepocapa. Pyroclastic flows also descended the E flank on 10 November. The Washington VAAC reported an ash plume that morning below 5.2 km altitude drifting WSW at 15 knots. The plume was visible in satellite imagery extending for 110 km to the coast, and possibly out over the ocean to 185 km. By late in the day, ongoing lava flows and rockfalls were causing ash to rise to 6.1 km altitude and the winds were moving the ash out of the valleys around 140 km SW of Fuego. Ashfall was reported from communities as far as 90 km to the west including San Andrés Osuna (12 km SW), El Zapote (10 km S), Siquinala (20 km SW), Santa Lucia Cotzumalguapa (22 km SW), Mazatenango (87 km W), Patulul (30 km W), and Cocales (35 km W).

Strong multi-pixel MODVOLC signatures increased again between 25 November and 2 December and correlate with INSIVUMEH's reporting of large and strong explosions and new lava flows beginning on 29 November. The Washington VAAC reported ongoing emissions to 5.2 km altitude on 25 November which dissipated quickly. INSIVUMEH noted lava fountains rising to 500 m above the crater, feeding four lava flows that traveled 3 km down the Ceniza, Trinidad, Las Lajas, and Santa Teresa drainages on 29 November. A fifth lava flow was seen the next day along with small pyroclastic flows in the Honda drainage on the E flank. A new pulse of ash emissions to 5.5 km began on 30 November extending 45 km SW from the summit and continued through 1 December drifting more to the NW into S Mexico before dissipating.

Discrete ash emissions to 5.5 km altitude which quickly dissipated were observed in webcam imagery on 9 December 2015. Late the following day, another plume was spotted at the same elevation drifting 37 km NNE. Activity increased during the night of 14-15 December, characterized by an increased number of explosions (4-6 per hour). Ash plumes rose almost 1 km high and drifted 10-15 km NE, E, and SE. Two 800-m-long lava flows were active in the Trinidad and Santa Teresa drainages. Strong multi-pixel MODVOLC alerts appeared daily from 11-18 December. The Washington VAAC observed ongoing emissions on 16 December at 5.2 km altitude; they drifted as far as 280 km SW of Fuego. Lava flows remained active in the Las Lajas, Trinidad, and Santa Teresa drainages. Activity decreased toward the end of the month with modest ash emissions rising less than a kilometer above the summit, and incandescent material rising 150 m above the crater.

Table 12. Towns and drainages around Fuego and their distance and direction from the summit.

Volcán de Fuego has been erupting continuously since 2002. Historical observations of eruptions date back to 1531, and radiocarbon dates are confirmed back to 1580 BCE. These eruptions have resulted in major ashfalls, pyroclastic flows, lava flows, and damaging lahars. Fuego was continuously active from June 2014-December 2015. Ash plumes rose to 6 km altitude, ashfall was reported in communities as far as 90 km away, pyroclastic flows descended multiple drainages at least four times, Strombolian activity rose to 800 m above the summit, lava flows descended a few kilometers down five different drainages numerous times, and three different lahars damaged roadways (BGVN 42:05). This report continues with a summary of similar activity during January-June 2016. In addition to regular reports from INSIVUMEH, the Washington Volcanic Ash Advisory Center (VAAC) provides aviation alerts. Locations of towns and drainages are listed in table 12 (BGVN 42:05).

Daily weak and moderate explosions generating ash plumes to about 800 m above the summit (4.6 km altitude) that dissipated within about 10 km were typical activity for Fuego during January-June 2016. In addition, ten eruptive episodes were recorded during this time. Each episode lasted 24-72 hours, with all but one including incandescent material rising 200-400 m above the summit feeding lava flows down the larger drainages for several kilometers. Most also included pyroclastic flows down the larger drainages. One of the episodes consisted of only large pyroclastic eruptions (with an accompanying ash plume) that issued directly from the summit crater and down the ravines; all included ash plumes rising over 5 km in altitude. Several lahars were reported during late April-June.

Activity during 30 December 2015. INSIVUMEH reported a significant increase in activity on 30 December 2015. A series of pyroclastic flows descended the Las Lajas and El Jute drainages on the SE flank, and a dense ash plume rose to 5 km altitude and drifted 20 km W. Ashfall was reported in multiple communities on the flanks, including Panimache I and II (8 km SW), Morelia (9 km SW), and Santa Sofía (12 km SW).

Activity during January 2016. Two eruptive episodes with explosions that generated ash plumes, pyroclastic flows, Strombolian activity, lava flows, and ashfall were documented by INSIVUMEH during January 2016. The first eruption began with an increase in seismicity early in the morning of 3 January. Moderate to strong explosions were accompanied by an ash plume that rose to 4.8 km altitude (about 1 km above the summit) and drifted W and SW. Two lava flows emerged from the summit crater and traveled down the Las Lajas and Trinidad ravines. Moderate to strong explosions continued during 3 January. By the afternoon, dense plumes of ash were reported at 6 km altitude drifting SW and SE more than 40 km. Ashfall was reported in the villages of Panimaché I and II, Morelia, Santa Sofia, El Porvenir, La Rochela, Osuna, El Zapote and Rodeo. Also later in the day, incandescence was observed 400 m above the crater; it fed three lava flows in the Santa Teresa, Trinidad, and Las Lajas canyons that reached 2.5 km in length. Eruptive activity diminished after about 37 hours with weak bursts of ash rising to 4.6-4.7 km altitude on 5 January that drifted S, SW, and SE.

A smaller explosive event during 15-17 January produced block avalanches and created ash plumes that rose 450-750 m above the crater and drifted up to 12 km N and NE; four to five explosions per hour were detected. The second eruptive episode began with increased activity on 19 January; incandescent material was ejected 400-500 m above the summit, generating new lava flows to the same three canyons as the earlier eruption (Santa Teresa, Trinidad and Las Lajas) (figure 36). Ash emissions rose to 4.9 km altitude and drifted NE. Pyroclastic flows also descended the Las Lajas and El Jute canyons (figure 37).

Figure 37. A pyroclastic flow descends towards the Las Lajas and El Jute ravines on the SE flank of Fuego on 19 January 2016 in this thermal image captured by INSIVUMEH. Courtesy of INSIVUMEH (Informe Mensual De La Actividad Del Volcán Fuego, January 2016).

The second episode continued throughout 20 January 2016 when the largest ash plume rose to 6.7 km altitude and drifted NE more than 90 km according to the Washington VAAC. Ashfall was reported in San Miguel, Las Dueñas, Alotenango, Acatenango, and Antigua. Ash plumes from the pyroclastic flows also generated ashfall on the S and SW flanks (figure 38). By the morning of 21 January, the lava flows had ceased advancing at about 3 km length, although a hot spot was still clearly visible in satellite imagery. Weak explosions generated ash plumes that rose only a few hundred meters above the summit and drifted NNE. During January, the Observatorio del Volcan de Fuego installed a second webcam on the SE side of Fuego at the Finca La Reunión, a resort about 8 km from the summit. The first webcam is located about 10 km SW of the summit at the Observatorio del Volcan de Fuego in the community of Panimache.

Figure 38. A pyroclastic flow on 20 January 2016 travels down the SE flank of Fuego, creating an ash cloud in the ravine. Additional ash emissions drifted in multiple directions. A recent lava flow is also visible in the ravine. View is from the La Reunión webcam, 8 km SE of the summit. Courtesy of INSIVUMEH (Informe Mensual De La Actividad Del Volcán Fuego, January 2016).

Activity during February-March 2016. Explosions increased in number and energy on 5 February 2016, classified by INSIVUMEH as the 3rd episode of the year. Six moderate to strong explosions per hour were reported, sending ash emissions to 4.5 km altitude, drifting W, NW, and N more than 12 km, and avalanche blocks down the flanks to the base. The third eruptive episode of the year began with moderate explosions on 9 February 2016; it generated ash plumes which rose to 4.7 km altitude and dispersed up to 35 km NNW. Ashfall was reported in Chimaltenango, Zaragoza, Ciudad Vieja, San Pedro las Huertas, San Miguel Las Dueñas, San Juan Alotenango, Antigua Guatemala and the Capital City as far as 35 km N and NE. The explosions were accompanied by incandescent material rising to 300 m above the summit and feeding lava flows that traveled towards the Trinidad, Las Lajas, and Santa Teresa canyons, reaching lengths of 800 to 3,000 meters (figure 39).

The following day (10 February 2016), pyroclastic flows descended the El Jute and Las Lajas ravines (figure 40) while ash plumes rose to 5.2 km altitude and incandescent material was ejected 400 m above the crater. Although activity decreased throughout the day, explosions continued to generate ash plumes to 4.9 km altitude that dispersed ash up to 45 km N and NE. Minor ash emissions were reported by the Washington VAAC on 17 February at 4.6-4.9 km altitude drifting SE about 40 km, and on 24 February at 4.6 km drifting about 25 km SW.

On 29 February 2016, moderate to strong explosions at a rate of 6-10 per hour were heard more than 14 km away. They were accompanied by an ash plume that rose to 4.8 km and drifted 12 km E, and a lava flow that traveled 500 m towards Las Lajas ravine. This 4th eruptive episode (according to INSIVUMEH) lasted more than 72 hours (figure 41). On 2 March, several ash plumes rose to different altitudes and dispersed in different directions. The largest ash plume, was observed by the Washington VAAC at 7.3 km altitude; it was visible 400 km N before it dissipated into weather clouds. Lower altitude plumes rose to 4.6 km and drifted 75 km SW before dissipating. Ash fell in the communities of Morelia, Santa Sofia, La Rochela, Panimaché I and II, Sangre de Cristo, La Soledad and Yepocapa. The incandescent activity fed two lava flows; the first in the direction of Las Lajas reached 3 km, the second flowed towards El Jute ravine and reached 2 km in length. Pyroclastic flows also travelled down these two canyons and block avalanches descended the Honda Canyon. Explosive activity diminished during 3-6 March; ash emissions rose to 550 m above the summit and drifted 8-10 km W, SE, and SE.

During 10 March 2016, moderate to strong Vulcanian explosions generated an ash plume that rose to 4.4 km altitude and drifted E. The Washington VAAC observed ash emissions in multispectral satellite imagery on 15 March at 4.3 km altitude extending about 80 km SW from the summit as well as hot spots and pyroclastic flows visible in the INSIVUMEH webcam. An increase in activity on 21 March generated weak and moderate explosions that produced ash plumes that rose to 4.3-4.7 km and drifted W. This activity was recorded as an increase in RSAM tremor amplitude and duration at the FG3 seismic station, but was not considered an eruptive episode by INSIVUMEH (figure 42).

Figure 42. Increases in RSAM tremor amplitude and duration at Fuego were recorded during 21 and 22 March, and eruptive episode 5 was recorded during 26 and 27 March 2016. Courtesy of INSIVUMEH (Informe Mensual De La Actividad Del Volcán Fuego, Marzo 2016).

Eruptive episode 5 began on 26 March 2016 and lasted more than 24 hours (figure 42). Strombolian eruptions rose up to 500 m above the crater (figure 43), feeding three lava flows that traveled 2 km down Las Lajas, 1.3 km down the Santa Theresa, and 1 km down the Trinidad ravines. Ash plumes rose to 6.1 km altitude and drifted up to 150 km W (figure 44); ash fell on the villages of Morelia, Santa Sofia, San Predro Yepocapa, Panimaché I and II. By the end of 27 March, eruptive activity had diminished to background conditions, which included weak and moderate explosions generating ash plumes to about 800 m above the summit (4.6 km altitude) that dissipated within about 10 km WSW. On 29 March ashfall was reported Sangre de Cristo and Panimaché I and II.

Activity during April-May 2016. The Washington VAAC reported diffuse volcanic ash emissions in satellite and webcam imagery on 2 April 2016. The ash plume drifted W at 4.3 km altitude, and extended 75 km from the summit before dissipating. Increased eruptive activity during 6-7 April 2016 resulted in moderate and strong explosions which produced ash plumes rising to 4.6-4.8 km altitude that drifted W and SW 15 km. The explosions were audible more than 20 km from the volcano; roofs and windows vibrated within 12 km. INSIVUMEH received reports of ashfall from the villages of Morelia, Sangre de Cristo, and Panimche I and II.

An explosion on 8 April created an ash plume that rose to 5.8 km and drifted SSW about 35 km. Successive bursts of ash on 9 April rose to 4.9 km altitude and drifted W. Emissions on 11 April were reported at 4.3 km altitude about 15 km SW from the summit; the next day they rose to 4.9 km and drifted SW to a distance of 45 km. INSIVUMEH reported variable activity beginning on 11 April with high levels of explosive activity on 12 April marking the beginning of the sixth eruptive episode of the year, which lasted for three days. An incandescent fountain persisted 100-300 m above the crater and fed two lava flows during the event; one traveled 2 km down the Las Lajas ravine, and the other reached 1 km in length in the Santa Teresa ravine. Avalanches were constant along the flanks during this episode. Continuous ash emissions were observed as well; plumes generally rose no higher than 5.8 km (2 km above the summit). Ashfall was reported in La Rochela, Ceylon, Morelia, Hagia Sophia, Sangre de Cristo, Panimaché I and II. On 13 April the ash plume extended 185 km SW from the summit. A brilliant hotspot was observed in satellite imagery on 14 April after which no further VAAC reports were issued until early May. On 29 April, after more than a week of rain, a lahar descended the Las Lajas drainage but no damage was reported.

Activity at Fuego increased significantly during May 2016, and included three eruptive episodes that generated ash plumes, pyroclastic and lava flows, and increased rainfall that resulted in lahars. Ash plumes rose above 5.5 km altitude (more than 2 km above the summit) and dispersed to the S, SW, and SE. Seismic activity increased on 5 May in the form of internal vibrations caused by lava which flowed more than 1.2 km down the Las Lajas ravine, and moderate to strong explosions that produced ash plumes which rose to 4.8 km altitude and drifted S for 12 km. The Washington VAAC reported diffuse ash extending 65 km SE from the summit.

The 7th eruptive episode of the year began on 6 May 2016 with incandescent material rising 300 m above the summit crater, causing two lava flows. One traveled down Las Lajas ravine more than 3 km; the second descended the Trinidad ravine for 1.5 km. Block avalanches were constant around the crater rim. The episode lasted for more than 32 hours (figure 45); the moderate to strong explosions ejected ash to altitudes above 5.5 km that drifted S and SW. Ashfall was reported in Escuintla and its surroundings. There were no pyroclastic flows during this episode. The Washington VAAC reported emissions extending 65 km SE of the summit at 5 km altitude on 6 May.

Figure 45. RSAM values during 2 May-6 June 2016 helped INSIVUMEH to define eruptive episodes for 2016 at Fuego, along with observed activity. Eruptive episode 7, consisting of Strombolian activity, lava flows, and ash plumes, occurred during 6-7 May 2016. Episode 8 comprised ash plumes and several large pyroclastic flows that descended the S flank during 18 and 19 May, but no seismic explosive activity. Increases in explosive activity on 21 May marked the beginning of episode 9, which lasted through 23 May 2016 and included incandescent fountains, lava flows, and ash plumes. Courtesy of INSIVUMEH (Informe Mensual De La Actividad Del Volcán Fuego, Mayo 2016).

The next eruptive episode (8) did not involve seismic explosive activity (figure 45). Instead, several large pyroclastic flows overflowed the crater rim on 18 and 19 May 2016 and descended the flanks towards Las Lajas and Honda ravines (figure 46) resulting in ashfall reported to the S, SW, and W, in villages more than 30 km away. A large ash plume reached more than 5.5 km altitude and drifted 15 km SSW on 19 May (figure 47). Ashfall was reported in the villages of El Rodeo, La Rochela, Osuna, Panimaché, Morelia, Sangre de Cristo and Yepocapa. By late in the day, the Washington VAAC noted that the plume was centered about 90 km SW at 5.8 km altitude.

Figure 47. An ash plume drifts SW from Fuego on 19 May 2016 after a series of pyroclastic flows and ash emissions sent ash plumes to over 5 km altitude. The Operational Land Imager instrument on Landsat 8 captured this image. Courtesy of NASA Earth Observatory.

The ninth eruptive episode of 2016 generated incandescent fountains 200-300 m above the summit; they fed a 2-km-long lava flow down the Las Lajas ravine (figure 48). Seismic activity began to increase on 21 May and lasted through 23 May (see figure 45). Moderate and strong explosions created an ash plume that rose to 5.5 km altitude and drifted SW and W. The Observatory reported ashfall in Morelia, El Porvenir, Santa Sofia, Los Yucales, Panimaché I and II. The Washington VAAC reported an ash plume visible in satellite imagery at 5.5 km altitude, drifting 75 km S beyond the coast on 23 May 2016. A lahar descended the Las Lajas ravine on 20 May and was recorded by the seismic station FG3, but no damage was reported.

Activity during June 2016. A significant rainfall combined with the plentiful ash from recent pyroclastic flows, resulted in lahars descending Las Lajas and El Jute ravines on 5 June 2016. They transported blocks, branches, and tree trunks, and a strong sulfur smell was reported by nearby residents. Another lahar was reported on 18 June that was 15 m wide and had a 1.5-m-high front. An increase in seismic activity during the afternoon of 24 June signaled the beginning of eruptive episode 10. This was followed by about 30 hours of moderate to strong explosive activity that could be heard and felt as far as 12 km away. A dense ash plume on 25 June rose to 5.5 km altitude and drifted S, SW, and W more than 40 km. Ashfall was reported in San Pedro Yepocapa, Sangre de Cristo, Morelia, Santa Sofia, Panimaché I and II. The Washington VAAC observed the ash plume in multispectral imagery on 25 June extending 120 km WSW from the summit. NASA Goddard Space Flight Center captured a small but distinct SO2 plume from Fuego on 25 June as well (figure 49). Incandescent material rose 300 m above the summit crater during this episode and fed three lava flows; the first descended Las Lajas ravine 2.5 km, the second traveled 2.3 km down El Jute ravine, and the third flowed down Taniluyá ravine for 600 meters. Seismic activity from episode 10 decreased on 26 June.

Figure 49. A small but distinct SO2 anomaly was measured from Fuego on 25 June 2016. INSIVUMEH reported the 10th eruptive episode of the year during that time with a dense ash plume and lava flows emerging from the summit crater. Courtesy of NASA Goddard Space Flight Center.

Volcán de Fuego has been erupting continuously since 2002. Historical observations of eruptions date back to 1531, and radiocarbon dates are confirmed back to 1580 BCE. These eruptions have resulted in major ashfalls, pyroclastic flows, lava flows, and damaging lahars. Fuego was continuously active from January to June 2016. Daily explosions that generated ash plumes to within 1 km above the summit (less than 5 km altitude) were typical. In addition, there were ten eruptive episodes that included Strombolian activity, lava flows, pyroclastic flows, and ash plumes rising above 5 km altitude (BGVN 42:06). Every month, lahars flowed down several drainages. This report continues with a summary of similar activity during July-December 2016. In addition to regular reports from the Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia (INSIVUMEH), the Washington Volcanic Ash Advisory Center (VAAC) provides aviation alerts. Locations of many towns and drainages are listed in table 12 (BGVN 42:05).

Activity during July-December 2016 was very similar to the previous six months. Background activity included daily explosions, and ash emissions that often generated minor ashfall in communities within 15 km, generally to the SW. Strombolian activity sent material 300 m above the crater, and block avalanches down the flanks. Six eruptive episodes occurred during the second half of 2016, with characteristics very similar to the ten that occurred during the first half of the year (table 13). The episodes usually lasted around 48 hours. During the eruptive episodes, the amplitude and frequency of explosions increased to several per hour, and ash emissions that rose 1-3 km above the summit crater (4.8-7.8 km altitude) distributed ash tens of kilometers away. Diffuse ash plumes were often visible in satellite imagery several hundred kilometers from the volcano. Each episode was also accompanied by Strombolian activity that sent incandescent material 200-500 m above the summit crater, creating lava flows that descended major drainages. Episodes 11 and 16, in July and December, also included pyroclastic flows. The thermal signature recorded in the University of Hawaii's MODVOLC thermal alert system closely correlated with the increased heat flow from the lava flows during the eruptive episodes. Numerous lahars descended major drainages after heavy rains during August, but no damage was reported. A modest lahar was reported near the end of September.

Table 13. Eruptive episodes at Fuego during 2016. Details of episodes 1-10 are described in BGVN 42:06, episodes 11-16 are discussed in this report. The eruptive episode number is just for 2016 and was assigned by the Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia (INSIVUMEH).

Dates

Episode

Max Ash Plume altitude

Ash Plume drift

Ash Plume max distance

Ashfall report locations

Lava Flow drainages

Lava Flow lengths

Incandescence above crater

Pyroclastic Flow drainages

3-5 Jan 2016

1

6.0 km

SW, SE, S

40 km

8-12 km SW and SE

Las Lajas (SE), Trinidad (S), Santa Teresa (S)

2.5 km

400 m

--

19-21 Jan 2016

2

6.7 km

NE

90 km

8-18 km NE, 12 km NW

Las Lajas (SE), Trinidad (S), Santa Teresa (S)

3 km

400-500 m

Las Lajas (SE), El Jute (SE)

9-10 Feb 2016

3

5.2 km

NNW

40 km

45 km N, NE

Las Lajas (SE), Trinidad (S), Santa Teresa (S)

800 m-3 km

300-400 m

Las Lajas (SE), El Jute (SE)

29 Feb-3 Mar 2016

4

7.3 km

N

400 km

10 km SW, N, NW

Las Lajas (SE), El Jute (SE)

2-3 km

yes

Las Lajas (SE), El Jute (SE)

26-27 Mar 2016

5

6.1 km

W

150 km

9-12 km, SW, NW

Las Lajas (SE), Santa Theresa (S), Trinidad (SE)

2.0, 1.3, 1.0 km

500 m

--

12-14 Apr 2016

6

5.8 km

SW

185 km

10 km SW

Las Lajas (SE), Santa Theresa (S)

2.0, 1.0 km

100-300 m

--

6-7 May 2016

7

5.5 km

S, SW, SE

65 km

21 km SE

Las Lajas (SE), Trinidad (SE)

3.0 km, 1.5 km

300 m

--

18-19 May 2016

8

5.5 km

SSW

90 km

30 km NW, S, SW, W

--

--

--

Las Lajas (SE), Honda (E)

21-23 May 2016

9

5.5 km

SW, W, S

75 km

8-12 km, SW, ENE

Las Lajas (SE)

2 km

200-300 m

--

24-26 Jun 2016

10

5.5 km

S, SW, W

120 km

8-12 km NW, SW

Las Lajas (SE), El Jute (SE), Taniluyá (SW)

2.5 km, 2.3 km, 600 m

300 m

--

28-29 Jul 2016

11

5.5 km

SW, W, NW

250 km

12 km SW, W, 27 km NW

Santa Teresa, Las Lajas

1.5 km, 3 km

500 m

Santa Teresa

6-8 Sep 2016

12

5.0 km

W, SW

25 km

SW, W

Las Lajas, Taniluyá

1.2 km, 500 m

300 m

--

27-28 Sep 2016

13

5.0 km

W, SW

20 km

--

Las Lajas, Santa Theresa

1.5 km, 1.8 km

300 m

--

29-30 Oct 2016

14

7.0 km

W, NW

110 km

10 km NW, SW

Las Lajas, Santa Teresa, Taniluyá

2.0 km, 300 m, 500 m

400-500 m

--

20-21 Nov 2016

15

5.0 km

SSW

175 km

8-12 km SW

Trinidad, Ceniza, Las Lajas

1.0 km, 2.0 km, 2.5 km

300 m

--

20-21 Dec 2016

16

5.2 km

W, SW

230 km

8-12 km SW

Santa Teresa, Taniluyá, Trinidad, Las Lajas

2.5, 2.0, 600, 1.8

400 m

3.5 km Taniluyá

Activity during July 2016. Explosions of incandescent material from the summit crater of Fuego were constant during July 2016, according to INSIVUMEH. On 5 July, an increase in the number of explosions per hour led to an ash plume rising to 4.5 km altitude and drifting W and SW. Incandescent blocks reached the vegetation on the W flank a few hundred meters from the summit. Ashfall was reported in the villages of Morelia, Santa Sofia, Sangre de Cristo (all around 10-12 km SW), and San Pedro Yepocapa (9 km NW). Another increase in activity on 15 July resulted in eight weak-to-moderate explosions per hour, which generated ash plumes that rose to about 4.3-4.8 km altitude and drifted more than 15 km W and SW; ash fell on the flanks in those directions. The Washington VAAC reported ash emissions rising to 4.6-5.2 km altitude, and MODVOLC issued one thermal alert. On 17 July, the Washington VAAC reported an ash emission drifting about 18 km W at 4.9 km altitude. Another ash emission was observed in satellite imagery on 19 July, at 5.2 km altitude drifting NW. The Washington VAAC also reported that the webcam showed lava on the flank near the summit that day.

Eruptive episode 11 began on 28 July 2016 and lasted for about 48 hours. Moderate-to-strong explosions expelled ash plumes to 5.5 km altitude that eventually drifted more than 250 km SW, W, and NW. The INSIVUMEH webcam at Finca La Reunion (SE) captured an image of the ash plume accompanied by a pyroclastic flow which descended the Santa Teresa ravine (barranca) around midday on 29 July (figure 50). Incandescent material was ejected about 500 m above the crater and fed two lava flows; one traveled 1.5 km down the Santa Teresa ravine, and the other traveled 3 km down the Las Lajas ravine. Some of the villages that reported ashfall included Sangre de Cristo, San Pedro Yepocapa, and Patzún (27 km NW). The Washington VAAC observed the ash plume in the early morning of 29 July extending 30 km WNW from the summit at 5.8 km altitude. By late morning, the plume had risen to 6.7 km altitude and was visible 150 km NW. The plume altitude dropped later in the day to 5.2 km, and the drift direction changed more toward the W. The farthest edge of the plume was faintly visible over 250 km W before it dissipated that evening. Incandescent explosions continued into the night, but had subsided by the next morning. A MODVOLC thermal anomaly signal first appeared on 26 July and persisted through 31 July; there were 17 thermal alert pixels reported on 29 July.

Figure 50. An ash plume rises from the summit of Fuego on 29 July 2016 while a small pyroclastic flow descends a drainage on the SE flank, as seen from the Finca la Reunion webcam. Eruptive episode 11 lasted from 28 to 30 July. Courtesy of INSIVUMEH (Informe Mensual De La Actividad Del Volcán Fuego, Julio 2016).

Activity during August 2016. Weak and moderate explosions that generated ash plumes characterized activity during August 2016. Although a few strong explosions were recorded, there were no distinct eruptive episodes documented by INSIVUMEH. Constant rains, however, led to several lahars descending the major ravines. Persistent steam plumes rose to 4.2 km and drifted W and SW. Weak-to-moderate explosions with ash reached 4.3 to 4.8 km altitude, and drifted more than 15 km SW and W before dissipating. Ashfall was reported primarily in the communities of Sangre de Cristo, Yepocapa, Morelia, Hagia Sophia, and Panimaché I and II. Incandescent material was ejected 300 m above the crater, and generated weak-to-moderate avalanches within the crater.

The Washington VAAC reported an ash plume visible in satellite imagery on 7 August at 4.9 km altitude extending about 10 km WNW from the summit. On 11 August, a narrow plume was spotted in both visible and multispectral imagery extending about 80 km W at the same altitude. A puff of volcanic ash appeared in clear satellite and webcam images drifting W at 4.9 km on 19 August. A series of ash emissions were spotted on 20 August in satellite imagery. The head of the plume was about 35 km W of the summit. The highest altitude plume reported by the Washington VAAC during August was at 5.8 km on 25 August, drifting 25 km W. A single MODVOLC thermal alert was also recorded that day. On 15 and 16 August moderate-to-large lahars descended the Las Lajas and El Jute ravines, carrying blocks as large as 3 m in diameter, tree trunks, branches, and other debris. Another lahar recorded on 28 August descended the Santa Teresa tributary of the Pantaleón River, where the residents noted the warm temperature of the debris.

Activity during September 2016. Two eruptive episodes took place during September 2016. Episode 12 began on 6 September and lasted about 48 hours. Moderate-to-strong explosions generated ash plumes that rose to 5 km altitude and drifted 25 km W and SW. Incandescent material rose to 300 m above the crater and fed two lava flows, one traveled 1.2 km down the Las Lajas ravine (figure 51), and the other travelled 500 m down the Taniluyá. The Washington VAAC reported an ash plume, identified in satellite imagery, on 7 September moving WSW at 4.9 km altitude. MODVOLC thermal alerts were issued during 4-8 September, with 10 alerts appearing on 8 September.

Figure 51. On 7 September 2016, the Operational Land Imager (OLI) on Landsat 8 captured this image of lava flowing down the Las Lajas and Santa Teresa ravines at Fuego during eruptive episode 12. The image is a composite of natural color (OLI bands 4-3-2) and shortwave Infrared (OLI band 7). Shortwave infrared light (SWIR) is invisible to the naked eye, but strong SWIR signals indicate increased temperatures. Courtesy of NASA Earth Observatory.

A bright hotspot in satellite imagery was reported by the Washington VAAC on 25 September 2016. A modest lahar descended the Santa Teresa ravine on 26 September, carrying 50-cm-diameter blocks, branches, and tree trunks; it was 10 m wide and 1 m high. Eruptive episode 13 began the next day, 27 September 2016, with moderate-to-strong explosions, and an ash plume that rose to 5 km altitude and drifted more than 20 km W and SW (figure 52). Incandescent material rose 300 m above the crater, feeding two lava flows. Lava traveled 1.5 km down the Las Lajas ravine (figure 53) and 1.8 km down the Santa Teresa ravine. A fissure developed on the S flank of the crater rim, and new fumarolic activity was observed during the day. Constant rumbling noises were audible in the areas of Finca Palo Verde, Sangre de Cristo, and San Pedro Yepocapa on the W and SW flanks. The Washington VAAC reported an intense hotspot in shortwave imagery. Activity subsided on 28 September. A strong multi-pixel thermal alert signal appeared in the MODVOLC data from 24-29 September.

Activity during October 2016. Six to ten explosions per day were recorded at Fuego during October 2016. Some of them generated ashfall on the SW flank. Episode 14, which began at the end of the month, produced three lava flows and strong explosions with an ash plume that rose to 7 km altitude and drifted N and NW. The Washington VAAC reported multiple ash emissions at 5.2 km altitude on 3 October, with the furthest one extending 35 km S. The next day, ash emissions were observed at 4.9 km altitude and drifted 22 km SSE. Pyroclastic flows were seen in an INSIVUMEH webcam on 10 October. They also reported ashfall in nearby communities that day.

Incandescent material rose 150-200 m above the summit crater on 28 October, and lava traveled 500 m down the Las Lajas ravine. Episode 14 began the next day with a strong explosion that generated an ash plume to 7 km altitude that drifted 110 km W and NW. Constant loud rumbling was reported up to 15 km from the volcano, and ashfall was reported in San Pedro Yepocapa, Sangre de Cristo, and La Conchita. Three incandescent lava fountains were seen in the early hours of 30 October (figure 54). The first, 450 m above the crater, fed a 2-km-long flow in the Las Lajas ravine. The second fountain rose to 250 m and fed a flow that traveled 300 m down the Santa Teresa canyon. The third fountain rose 200 m and formed a flow that traveled down the Taniluyá drainage for 500 m. Activity declined during the night of 30 October, but weak and moderate avalanches of incandescent material continued into the first part of the next day.

The first ash emissions of episode 14 were visible in satellite imagery on 29 October, extending roughly 45 km NNW from the summit. By early the next day, the ash emissions were detected at 7.3 km altitude, based on a pilot report. They extended about 110 km NNW from the summit. Later in the day, the plume had lowered to 5 km altitude and drifted 15 km N and NW. A single MODVOLC thermal alert was reported on 13 October, but a lengthy series of multi-pixel alerts were generated during 24-31 October, including 19 pixels on 30 October at the peak of episode 14.

Activity during November 2016. Activity during November 2016 remained at background levels until the third week of the month; explosions increased in amplitude and frequency to as many as 15 per hour, leading to episode 15 which began on 20 November. The background levels of the second and third weeks included incandescent material rising to 300 m above the crater, causing avalanches down the flanks around the crater rim and continuous explosions of weak-to-moderate energy that generated ash plumes rising to altitudes between 4.3 and 4.7 km that drifted W and SW.

The Washington VAAC reported ash emissions in satellite imagery every day from 8 to15 November 2016. A plume was seen on 8 November rising to 4.6 km altitude and drifting 25 km SW. The next day, a plume at the same altitude drifted 45 km NW. On 10 November, a faint plume was seen in visible imagery, extending about 25 km NNW. A larger plume was visible in morning imagery on 11 November at 5.5 km altitude extending 35 km WSW. The next day, at the same altitude, a diffuse plume was visible 10 km W of the summit. Multiple emissions were spotted drifting W from the summit at 4.6-4.9 km altitude on 13 and 14 November. Two single MODVOLC thermal alerts were reported on 12 and 14 November. A hotspot was detected in satellite imagery on 15 November, along with continuing emissions to 4.6 km altitude that drifted within 10 km SW of the summit. On 17 November ashfall was reported in Morelia, Santa Sofia, and Panimache I and II. Emissions on 18 November rose to 4.7 km altitude and drifted 10 km SW, and on 20 November they rose to 4.9 km altitude and drifted 24 km from the summit (figure 55).

Figure 55. Strombolian eruption and ash emission at Fuego, looking S from Acatenango summit on the early morning of 18 November 2016. Photo copyright by Martin Rietze, used with permission.

Eruptive episode 15 began on 20 November with strong explosions that caused ash plumes to rise to 5 km altitude and drift as far as 175 km SSW and W, generating ashfall again in Morelia, Santa Sofia, and Panimache I and II. Three lava flows emerged from the 300-m-high Strombolian ejections; one traveled 1 km down the Trinidad ravine, one descended 2 km down barranca Ceniza, and the third flowed 2.5 km down barranca Las Lajas (figure 56). Numerous clouds of volcanic ash rose from block avalanches in Las Ceniza ravine on 20 and 21 November.

Figure 56. Eruptive episode 15 at Fuego occurred during 20-21 November 2016. An ash plume rose to 5 km altitude (top) before Strombolian activity 300 m high sent flows down three major ravines (bottom). These views from the rooftop of a hostel in Antigua (18 km NE) show the ravines in daylight during the afternoon of 20 November, and again around midnight that night as the incandescent material traveled downward. Photos copyright by Martin Rietze, used with permission.

The Washington VAAC reported an extremely large hotspot on 20 November 2016 (local time) in infrared imagery, along with ash emissions at 4.9 km altitude drifting SW to 65 km. Emissions at 3.8 km persisted into the night. By early morning on 21 November, they were visible extending 175 km W. A lengthy period of multi-pixel MODVOLC thermal alerts coincided with eruptive episode 15 during 17-23 November, and included 26 pixels on 21 November 2016. Eruptive activity decreased to background levels by 22 November, and only weak explosions and fumarolic activity were reported for the rest of the month.

Activity during December 2016. Weak-to-moderate explosions and ash plumes characterized background activity at Fuego during December 2016. Minor ashfall was regularly reported in communities located 8-12 km SW. Activity increased somewhat during 15-16 December, and eruptive episode 16 was recorded during 20-21 December. During episode 16, Strombolian activity created three lava flows that descended major ravines, and a large pyroclastic flow traveled 3.5 km from the summit, burning vegetation in its path.

The Washington VAAC reported an ash emission on 5 December at 5.8 km altitude drifting N. On 8 December, intermittent ash plumes were drifting W over the East Pacific Ocean at 6.1 km altitude. Remnants over 450 km W were seen in multispectral imagery by early on 9 December. Multiple new detached plumes continued moving WNW between 5.5 and 6.1 km altitude on 9 December. They were 80 km NW by late afternoon. New discrete emissions at 4.6 km altitude appeared in satellite imagery on 10 December, drifting W up to 130 km before dissipating.

During the afternoon of 20 December 2016, eruptive episode 16 began with moderate-to-strong ash emissions producing an ash plume that rose to 4.7 km altitude and drifted more than 15 km W and SW. Incandescent material rose 400 m above the crater, and bombs fell more than 300 m away. Block avalanches were concentrated in the Ceniza and Trinidad ravines. By the evening of 20 December, three lava flows had formed, in the Santa Teresa, the Taniluyá, and the Las Lajas ravines (figure 57). By the morning of 21 December, they were 2.5, 2.0, and 1.8 km long, respectively. During that day, strong explosions generated ash plumes that rose to 5.2 km altitude and drifted 18 km S, SW, W, and NW. Some of the communities that reported ash from this event included Panimaché, Morelia, Santa Sofia, Sangre de Cristo, San Pedro Yepocapa, and Palo Verde.

Around 1000 on 21 December, pyroclastic flows that descended the Taniluyá ravine generated an ash plume that rose 2 km and drifted W and SW. The flows traveled 3.5 km and were estimated to be 300 m wide. They descended the ravine at high speed and high temperature, burning everything in their path (figure 58). These were the first pyroclastic flows in several months. By the end of eruptive episode 16, the lava flow in the Taniluyá ravine had reached 2.8 km in length (figure 59).

Figure 58. A pyroclastic flow descends the Taniluyá ravine around 1000 local time on 21 December 2016 at Fuego during eruptive episode 2016. Courtesy of INSIVUMEH (Informe Mensual De La Actividad Del Volcán Fuego, Diciembre 2016).

Figure 59. Both a pyroclastic flow (3.5 km long, yellow outline) and a lava flow (2.8 km long, red outline) descended the Taniluyá ravine at Fuego during eruptive episode 16, from 20 to 21 December 2016. The white arrows indicate the ravine. The orange outline indicates the area where vegetation was destroyed by the pyroclastic flows. Courtesy of INSIVUMEH (Informe Mensual De La Actividad Del Volcán Fuego, Diciembre 2016).

MODVOLC thermal alerts were intermittent throughout December. They were recorded on 8 (2), 11 (2), 12, 14 (2), 16 (3), and 18 (3) December prior to episode 16. The biggest interval of multi-pixel alerts was during episode 16 from 20-22 December, and included 14 alerts on 21 December 2016. Additional single alerts were recorded on 25 and 29 December.

Guatemala's Volcán de Fuego was continuously active throughout 2016, and has been erupting since 2002. Historical observations of eruptions date back to 1531, and radiocarbon dates are confirmed back to 1580 BCE. These eruptions have resulted in major ashfalls, pyroclastic flows, lava flows, and damaging lahars. Daily explosions that generated ash plumes to within 1 km above the summit (less than 5 km altitude) were typical. In addition, there were 16 eruptive episodes that included Strombolian activity, lava flows, pyroclastic flows, and ash plumes rising above 5 km altitude (BGVN 42:10). Lahars flowed down several drainages during January-June, August, and September. Similar activity continued during January-June 2017 and included five eruptive episodes and numerous lahars. In addition to regular reports from the Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia (INSIVUMEH), the Washington Volcanic Ash Advisory Center (VAAC) provides aviation alerts. Locations of many towns and drainages are listed in table 12 (BGVN 42:05).

Explosions with ash emissions continued daily at Fuego during January-June 2017; five episodes of increased activity generated higher ash plumes, lava flows, and pyroclastic flows (table 14). The first eruptive episode of the year occurred on 25-26 January, consisting of two lava flows and an 8.6-km-long pyroclastic flow. The next eruptive episode, during 24-25 February, also generated two lava flows and a 7-km-long pyroclastic flow. Numerous ash plumes during March rose to within 1 km of the summit, and incandescent blocks traveled more than 200 m from the crater, but no lava or pyroclastic flows were reported. Eruptive episode 3 began on 1 April and included three lava flows up to 2 km long, and an ash plume reported at 9.1 km altitude. Significant lahars affected four ravines near the end of the month. Pyroclastic flows affected five ravines during eruptive episode 4 during 4-5 May, along with two lava flows, 1.5 and 1.2 km long. The Washington VAAC reported an ash plume from this event at 12.2 km altitude. Major lahars occurred eight times during May, transporting blocks up to a meter in diameter down the major drainages. There were seven periods of increased activity during June. The period of activity during 5-6 June, designated Episode 5, generated two lava flows (2 and 3 km long) and a pyroclastic flow.

Activity during January 2017. The last eruptive episode (16) of 2016, during 20-21 December, included Strombolian activity that produced three lava flows, a large pyroclastic flow, and ashfall in villages 10-12 km SW (BGVN 42:10). VAAC reports indicated ash emissions visible as far as 230 km SW during the episode. Intermittent ash emissions and thermal alerts were reported during the rest of December as well. Activity increased during January 2017, with ash falling mostly on the S and SW flanks. INSIVUMEH reported Vulcanian explosions on 3 and 4 January which contained abundant ash and sent plumes to 5 km above sea level that drifted NW, W, SW, and S (figure 60). Ashfall was reported in Sangre de Cristo, San Pedro Yepocapa, Santa Sofia, Morelia, Palo Verde Farm, Panimache I and II, La Rochelle, San Andrés Osuna, Siquinalá and Escuintla. Sounds and shockwaves were heard and felt 8 km from the volcano.

The Washington VAAC reported ash emissions at 4.3 km altitude (500 m above the summit) on 1 January extending about 35 km W of the summit early in the day. A second plume rose to 5.5 km and drifted a similar distance SE. A third ash plume a few hours later was spotted at 4.6 km altitude drifting W. By late in the day on 3 January, a broken plume of gas and ash was visible in satellite imagery 300 km SW. A well-defined plume on 4 January extended 90 km SW at 4.9 km altitude. Emissions rose to 5.8 km altitude on 5 January. Daily ash plumes during 2-8 January rose to 4.3-5.8 km and generally drifted W or SW up to 50 km. They also reported intermittent ash emissions in satellite imagery on 11 January, and visible in the webcam on 22 January.

The first eruptive episode of the year began on 25 January 2017 with constant explosions generating an ash plume that rose to 4.5 km altitude and drifted W and SW. Incandescence was visible 200 m above the crater, a lava flow traveled 1,000 m down the Ceniza canyon, and block avalanches descended the Ceniza and Trinidad ravines. Ash emissions later reached 5.5 km altitude and drifted W and SW more than 30 km. Strombolian activity ejected material 300 m above the crater and sent bombs more than 300 m from the crater. A second lava flow traveled down the Trinidad ravine later in the day. The Washington VAAC reported ash emissions during 25-28 January 2017 that rose to 4.6-5.5 km altitude extending over 200 km W. During the early morning of 26 January, a pyroclastic flow descended 8.6 km down the Ceniza canyon. INSIVUMEH estimated the volume of the flow to be over 11,000,000 m3 (figure 61). Extensive new pyroclastic flow deposits were observed filling parts of the ravine. A light layer of ash covered the vegetation in La Rochela as a result of the pyroclastic flow. INSIVUMEH reported ashfall in San Pedro on 26 January.

Figure 61. A pyroclastic flow at Fuego traveled 8.6 km down the Ceniza canyon during the early hours of 26 January 2017, part of the first eruptive episode of the year. The volume of the flow was measured by INSIVUMEH scientists as over 11,000,000 m3. Courtesy of INSIVUMEH (INFORME MENSUAL DE LA ACTIVIDAD DEL VOLCÁN DE FUEGO, ENERO 2017).

Activity during February 2017. An increase in activity on 2 February resulted in weak and moderate explosions that lasted 5-10 minutes and generated ash plumes that rose to 4.5 km altitude. The plumes drifted 15 km W and ashfall was reported in San Pedro Yepocapa and Sangre de Cristo. During 31 January-4 February the Washington VAAC noted several ash emissions (figure 62). They rose to altitudes ranging from 3.7-4.9 km and drifted S and W. Ash was visible 180 km SW on 2 February.

On the morning of 24 February, eruptive episode 2 began with explosions and ash plumes rising to 4.6 km altitude and drifting W and SW. Explosions were heard by nearby residents every few minutes, and by the evening two lava flows were observed in the Santa Teresa and Las Lajas ravines. Incandescence reached 300 m above the crater and fell more than 300 m from the crater on the flanks, generating block avalanches. By the next morning ash plumes were observed at 5 km altitude drifting more than 25 km NW, N, NE and E. A pyroclastic flow descended the Trinidad ravine on the morning of 25 February, and traveled about 7 km. Ash on the SE flank was reported in El Rodeo, El Zapote, La Réunion, Alotenango, and San Vicente Pacaya (figure 63). On 25 February, the Washington VAAC reported large areas of dissipating ash moving in multiple directions. Ash emissions at 5-5.2 km altitude were drifting 65 km NE, at 5.8 km altitude they were drifting 130 km NE and also SE, at 6.4 km they were moving S, and another simultaneous plume was observed at 7.6 km drifting 30 km SW.

Activity during March 2017. Daily weak and moderate explosions characterized activity during March 2017. Incandescence rose to 250 m above the crater and generated bombs and block avalanches that traveled more than 200 m from the crater (figure 64), but no new lava or pyroclastic flows were reported. INSIVUMEH reported an average of 17 explosions per day during the month, which generated ash plumes that rose to 4.4-4.9 km. Block avalanches were observed in the lower part of the Las Lajas ravine. Ashfall was reported in San Pedro Yepocapa, Sangre de Cristo, Palo Verde, Santa Sofía, Morelia, and Panimaché I and II. Three to six explosions per hour were recorded on 9, 10, 27, 29, and 31 March. The Washington VAAC reported ash emissions during 8-10, and 13 March. Plumes were observed rising to 4.6 km and moving W, 4.9 km moving S and SE, and 5.8 km drifting 80 km SE during these days. Lahars were reported on 17 and 21 March in the Las Lajas, Santa Teresa, and Ceniza ravines. The road to the village of La Rochela was cut off for a few days by the lahar in the Ceniza ravine.

Figure 64. Explosions generated ash plumes and block avalanches often during March 2017 at Fuego, including on 26 March in the early morning when this webcam image was taken. Courtesy of INSIVUMEH (INFORME MENSUAL DE LA ACTIVIDAD DEL VOLCÁN DE FUEGO, MARZO 2017).

Activity during April 2017. Persistent degassing during April sent steam emissions to 4.1-4.5 km altitude that dispersed in almost every direction, due to numerous changes in wind direction throughout the month. Weak to moderate Strombolian explosions created ash plumes that rose to 4.2-5.0 km and drifted primarily W and SW. Incandescence from the explosions was visible primarily at night and in the early morning around 100-300 m above the crater. The explosions also generated block avalanches that traveled more than 300 km from the summit. There were two spikes in explosive activity during April. The first, on 1 April, led to eruptive episode 3. The second, on 21 April, was less intense. These periods averaged 5-7 explosions per hour with ash plumes rising to 4.6-4.9 km and drifting in various directions.

Eruptive episode 3 began around midday on 1 April 2017, with Strombolian explosions that produced ash plumes up to 5 km that drifted more than 30 km NW, W, and SW; it lasted for about 16 hours. Ash fell in Sangre de Cristo, San Pedro Yepocapa, Santiago Atitlán, Chicacao, Mazatenango, and Retalhuleu. Lava flows traveled down the Las Lajas, Santa Teresa and Trinidad ravines as far as 2 km. The eruption was categorized by INSIVUMEH as a VEI 2 event with moderate to strong Strombolian explosions. The Washington VAAC reported an ash plume on 1 April that rose to 6.4 km altitude. The densest part of the plume was moving NW with some material fanning out to the NNE. They later revised their report with information that a new emission had risen to 9.1 km altitude and drifted NE. Ash emissions continued the next day with plumes moving NNW at 5.5 km and NNE at 8.2 km; bright incandescence appeared at the summit along with elevated seismicity. By the end of 2 April, the higher plume was diffuse as it dissipated over the far western Caribbean of the coast of Belize and Yucatan.

The Washington VAAC reported an ash emission to 4.5 km altitude on 21 April that extended 30 km NE of the summit. Occasional puffs of ash continued throughout the day and rose to 4.9 km altitude later in the day. By the next day, a plume was visible at 4.6 km extending 80 km E; it was later reported at 4.9 km altitude. By 23 April a faint plume extended 90 km S before dissipating. INSIVUMEH also reported ashfall in Palo Verde Farm, Santa Sofía, Morelia, and Panimaché I and II other times during the month.

Significant lahars affected several ravines on 20, 23, and 24 April 2017. Rain, hail and snowfall caused a lahar in Ceniza Canyon on 20 April (figure 65). On 23 April, lahars flowed down the Santa Teresa, Trinidad, Ceniza and Las Lajas ravines after 160 mm of rainfall in three days. These ravines are tributaries of the larger Pantaleón, Achíguate, and Guacalate rivers. Another lahar on 24 April in Ceniza Canyon was audible more than 1 km from the ravine.

Figure 65. View of Fuego after an intense rain and hailstorm on 20 April 2017 that caused a lahar in Ceniza Canyon. Photo by Francisco Juarea, courtesy of INSIVUMEH (INFORME MENSUAL DE LA ACTIVIDAD DEL VOLCÁN DE FUEGO, Abril 2017).

Activity during May 2017. Eruptive episode 4 began on 4 May 2017. A lava flow on the NE flank descended the Seca ravine for 1,500 m (figure 66). Explosions increased to 5-7 per hour, and were visible 200 m above the summit. Another lava flow descended 1.2 km down the Las Lajas ravine. Pyroclastic flows descended Barranca Seca, filling the channel and overflowing to the SE into Rio Mineral. They also affected Ceniza, Trinidad, El Jute, and Las Lajas canyons (figure 67) raising the imminent threat of lahars in these drainages. INSIVUMEH estimated that 14 million cubic meters of material was emplaced from the pyroclastic flows.

INSIVUMEH reported ash emissions during this episode as high as 6 km altitude. The ash dispersed S, SW, W and NW, and ashfall was reported in communities more than 25 km from the crater (figure 68). Energy levels decreased after about 24 hours. INSIVUMEH characterized the event as a VEI 3 eruption. The Washington VAAC was unable to observe the activity in satellite imagery due to cloud cover until the morning of 5 May, when they reported ash plumes moving SW at about 4.6 km altitude and also ENE at 5.5 km altitude. They reported a new, much higher ash plume midday on 5 May at 12.2 km altitude that was drifting E at about 50 km per hour, in addition to the lower level emissions around 4.6 km that drifted SW which generated ashfall in the immediate vicinity of the volcano. The Washington VAAC reported another ash emission on 7 May that rose to 4.9 km altitude and drifted SW about 10 km from the summit. Another plume appeared in satellite imagery the next day moving SW at 4.6 km about 15 km from the summit. The Washington VAAC reported no additional plumes until 31 May when satellite imagery showed a plume with possible ash extending about 25 km NE from the summit at 4.9 km altitude. Ashfall was reported during the month in Morelia, La Rochela, Santa Sofia, Sangre de Cristo, Palo Verde farm, Panimache I and II, San Pedro Yepocapa and Escuintla.

Figure 68. Ashfall from eruptive episode 4 at Fuego during 4-5 May 2017 was reported in communities more than 25 km from the volcano, and dispersed S, SW, W, and NW. Courtesy of INSIVUMEH (INFORME MENSUAL DE LA ACTIVIDAD DEL VOLCÁN DE FUEGO, Mayo 2017).

Moderate and strong lahars were recorded on six days in May (figure 69). Five took place in Seca barranca (13, 14, 19, 23, and 27 May), one in the Ceniza ravine (14 May), and two in Las Lajas canyon (both on 29 May). They transported very fine-grained material that had the consistency of wet concrete, and included blocks up to one meter in diameter.

Figure 69. A vehicle trapped in a lahar at Fuego in May 2017 surrounded by blocks as large as one meter in diameter. Courtesy of INSIVUMEH (INFORME MENSUAL DE LA ACTIVIDAD DEL VOLCÁN DE FUEGO, Mayo 2017).

Activity during June 2017. Weak and moderate daily explosions continued at Fuego during June 2017. They generated ash plumes that drifted more than 12 km, incandescence and block avalanches, and ashfall more than 30 km NW, W, and SW. Numerous lahars were also reported. The 20-25 daily explosions generally sent ash plumes to 4.2-4.5 km altitude that drifted mostly W and SW. The incandescence from Strombolian explosions generally extended 150-200 m above the crater (figure 70). Ashfall from these events was reported in in Morelia, Santa Sofia, Sangre de Cristo, La Rochela, and Panimache I and II.

Figure 70. A Strombolian explosion on 30 June 2017 at Fuego reached 150-200 m above the crater and sent avalanche blocks down the flanks. This was typical behavior for the month of June. Courtesy of INSIVUMEH (INFORME MENSUAL DE LA ACTIVIDAD DEL VOLCÁN DE FUEGO, Junio 2017).

There were seven periods of increased explosive activity during June 2017 (table 15), including eruptive episode 5. Many of the increases in energy levels were observed in the seismic record (figure 71) and reported by OVFGO (the Fuego Volcano Observatory). They noted an average of 5-8 explosions per hour during these events, and ash emissions rising to 4.6-4.9 km altitude, drifting W, SW, and S. None of the ash plumes reported by INSIVUMEH were observed by the Washington VAAC in satellite imagery due to weather clouds. The Washington VAAC did observe bright hotspots in shortwave imagery on 6 June.

Eruptive episode 5 for 2017 began during the late afternoon of 5 June. Moderate and strong Strombolian explosions generated an ash plume that rose to 6 km altitude and drifted more than 20 km W, SE, and NW from the crater. Sounds as loud as a freight train were reported nearby, and vibrations were felt in communities around the volcano. Lava flowed 3 km down the Santa Teresa ravine and 2 km down Ceniza canyon. Volcanic bombs rose 200 m high, and fell more than 300 m from the summit crater. Pyroclastic flows descended the Santa Teresa canyon on the W flank.

Thirteen lahars were reported during June (table 16). They descended the Santa Teresa, Mineral, Trinidad, Ceniza, Las Lajas, and El Jute ravines, tributaries of the Pantaleón, Achíguate and Guacalate rivers. Overflows from the drainages damaged several roads and river crossings in the region.

Satellite thermal data. The eruptive episodes reported by INSIVUMEH at Fuego during 2016 and the first half of 2017 are readily apparent in the MIROVA Log Radiative Power thermal data, and are also present going back at least to mid-2015 (figure 72). INSIVUMEH reported new lava flows and Strombolian activity each time (except for 2016 episode 8), which were the likely sources of the pulses of thermal activity. Details of the eruptive episodes for 2016 are discussed in BGVN 42:10 and 42:06.

Figure 72. MIROVA thermal anomaly graphs of MODIS infrared satellite data spanning 5 February 2015-19 September 2017 illustrating the recurring nature of eruptive episodes at Fuego. INSIVUMEH described 16 episodes during 2016, and five episodes during January-June 2017, shown as numbers over the red arrows. Episode 8 for 2016 is not shown; it was primarily a pyroclastic flow which did not generate the same thermal signal caused by lava flows during the other episodes. Courtesy of MIROVA.

Guatemala's Volcán de Fuego was continuously active throughout 2017, and has been erupting vigorously since 2002; historical observations of eruptions date back to 1531. These eruptions have resulted in major ashfalls, pyroclastic flows, lava flows, and damaging lahars. Reports of activity are provided by the Instituto Nacional de Sismologia, Vulcanología, Meteorología e Hidrologia (INSIVUMEH), and aviation alerts of ash plumes are issued by the Washington Volcanic Ash Advisory Center (VAAC). Satellite data from NASA, NOAA, and other sources provide valuable information about heat flow and gas emissions.

Activity remained high at Fuego throughout July-December 2017. Background levels of activity included frequent explosions (4-6 per hour) with incandescent material rising 150 m above the summit and sending blocks 200 m down the flanks. Block avalanches commonly traveled down the major ravines for hundreds of meters. Ash plumes regularly rose 500-1,000 m above the summit (4.3-4.8 km altitude); ashfall affected communities SW of the summit within 15 km every week. During the multiple short-lived (48-hour or less) eruptive episodes, the hourly explosion rates increased significantly (6-12 per hour), and incandescent material often rose 300 m above the summit; one or more lava flows would also travel more than a kilometer down major ravines. Higher ash plumes (often rising to 5-6 km altitude) during the eruptive episodes sent ash plumes drifting hundreds of kilometers in various directions causing ashfall in cities tens of kilometers away in various directions. Pyroclastic flows often accompanied the eruptive episodes. Seven episodes were reported by INSIVUMEH during July-December 2017 (table 17); they are clearly discernible as periods of higher heat flow in the MIROVA thermal anomaly data (figure 73) as well.

Table 17. Eruptive episodes at Fuego during July-December 2017. Information provided primarily by INSIVUMEH. Some ash plume information is from the Washington VAAC.

Figure 74. Incandescent material was ejected over a hundred meters above the summit of Fuego and blocks of material traveled hundreds of meters down the flank on 9 July 2017. Courtesy of INSIVUMEH and OVFGO (Reporte Semanal de Monitoreo: Volcán Fuego (1402-09), Semana del 08 al 14de julio 2017).

The Washington VAAC reported dense ash emissions seen in satellite data on 10 July extending WNW 60 km from the summit at 4.6 km altitude. They noted that ashfall was reported 10 km SW from the summit the following morning. The 6th eruptive episode of the year occurred on 11-12 July 2017. Explosions generated ash plumes that rose as high as 1.3 km above the crater and drifted 35 km W, and shock waves rattled nearby structures. Ash fell in areas to the SW. Two lava flows were fed by lava fountains 150-250 m high; one flow traveled 2.3 km down the Las Lajas drainage and another traveled 1.7 km down the Santa Teresa (SW) drainage. The increased activity levels lasted for about 31 hours, with tens of explosions. Weak-to-moderate explosions continued afterwards, generating ash plumes that rose 850 m and drifted 6 km W.

Multiple explosions continued generating ash plumes and block avalanches during 13-14 July. On 16 July, a 30-m-wide, 2-m-deep, hot lahar descended tributaries of the Pantaleón (W) drainage, carrying blocks more than 2 m in diameter, branches, and tree trunks. The lahars again overtook the road between communities on the SW flank, isolating the village of Sangre de Cristo (8 km WSW) and the Palo Verde estate. The Washington VAAC estimated that the ash plumes released early on 16 July rose to 5.2 km altitude, and drifted SE from the summit. By afternoon they had risen to 5.8 km and were drifting SW, extending about 75 km. Explosions during 17-18 July produced dense ash plumes that drifted 15 km W and NW causing ashfall in Panimache, Morelia, and Santa Sofía. Satellite imagery on 19 July showed an ash plume extending 65 km WNW of the summit in a narrow band at 4.3 km altitude. Similar plumes were reported daily between 19-23 July at 4.3-4.9 km altitude drifting generally W up to about 50 km before dissipating (figure 75).

Figure 75. Ash emissions were reported almost daily from Fuego during July 2017. A small pulse of ash on 20 July was captured on the Panimaché I webcam (10 km SW) in this view looking NE in the early morning. Courtesy of OVFGO-INSIVUMEH (Reporte Semanal de Monitoreo: Volcán Fuego (1402-09), Semana del 15 al 21 de julio 2017).

Activity during August 2017. MODVOLC thermal alerts that were issued on 28 and 30 July confirmed the continuing incandescent summit activity which produced block avalanches down the major drainages. Multiple daily alerts were also issued during 15 days of August. Coordinadora Nacional Para la Reduccion de Desastres (CONRED) reported increased activity on 4 August that included 300-m-high ejections of incandescent material and a lava flow that traveled 600 m down the Ceniza ravine. During 7-8 August two lava fountains rose 150 m high, prompting INSIVUMEH to announce the seventh effusive episode at Fuego in 2017. The fountains fed lava flows, 1.5 km and 700 m long, in the Ceniza and the Santa Teresa ravines (figure 76). Explosions (occurring at a rate of 6-8 per hour) produced ash plumes that drifted 20 km W, causing ashfall in Panimache, Morelia, Santa Sofía, El Porvenir, and Yepocapa. The Washington VAAC also noted increasing ash emissions on 7 August. Weather clouds prevented observations from satellite images on 7 and 8 August, but the VAAC reported a "" strong hotspot in infrared imagery on 8 August. Although the lava flow in the Ceniza drainage remained active, explosive activity decreased to an average of three explosions per hour the following week, with ash emissions rising to 4.4-4.6 km and drifting 10 or more km W and SW, bringing ashfall to communities on the W and SW flank.

Activity intensified again during 19-20 August, when constant explosions generated ash plumes that rose 2.3 km above the crater and drifted more than 50 km W and SW. INSIVUMEH reported that the eighth effusive episode at Fuego in 2017 began on 20 August and lasted for about 48 hours. Two lava fountains, each 300 m high, fed lava flows that traveled 1.4 km SSW down the Ceniza ravine and 1.2 km W down the Seca (Santa Teresa) ravine (figure 77). Incandescent block avalanches occurred throughout the crater. Pyroclastic flows (figure 78) were concentrated in the Santa Teresa ravine, possibly filling the drainage with deposits (similar to activity from 5 May) and increasing the chances for lahars. A bright hotspot was visible in satellite imagery from 19-21 August. Seismicity remained elevated through 21 August. During 21 August, the Washington VAAC reported the ash plume near 5.5 km altitude extending 75 km WNW. A remnant cloud of ash was detected in satellite imagery over 200 km WNW of the summit in extreme SE Mexico late on 21 August.

Figure 78. A pyroclastic flow descends the Santa Teresa ravine at Fuego during eruptive episode 8 on 21 August 2017 in this view from the Panimaché I webcam. Courtesy of OVGFO-INSIVUMEH (Reporte Semanal de Monitoreo: Volcán de Fuego (1402-09), Semana del 19 al 25 de agosto 2017).

INSIVUMEH reported that on 25 August multiple lahars descended the Pantaleón, Cenizas, El Jute, and Las Lajas drainages on Fuego's W, SSW, and SE flanks. The lahar in the Pantaleón river (fed by the Santa Teresa and El Mineral rivers) was 35 m wide, 2.5-3 m deep, and carried trees and blocks more than 2-3 m in diameter. The Cenizas lahar was about 25 m wide, 3 m deep, and carried blocks up to 2 m in diameter. The lahars in El Jute and Las Lajas drainages were 20 m wide, 1.5 m deep, and carried tree debris and blocks up to 2 m in diameter.

Explosions during 26-29 August generated ash plumes that rose as high as 950 m above the crater and drifted 7-12 km SW, W, and NW. The Washington VAAC reported near continuous emissions of ash on 28 August moving WSW and extending about 100 km at 4.6 km altitude, rising to 5.8 km altitude the following day. Incandescent material was ejected 100-200 m above the crater rim and caused avalanches of material around the crater area. Explosions were audible within a 20-km radius, and shock waves vibrated local structures. Ash fell in areas downwind including Panimache I and II, Morelia, Finca Palo verde, Sangre de Cristo, and El Porvenir. On 29 August, lahars 10 m wide and 1.5 m deep again descended the Santa Teresa and El Mineral drainages, carrying tree debris and blocks up to 2 m in diameter.

Activity during September 2017. Lahars were reported in the Santa Teresa and El Mineral drainages intermittently during September. Ash emissions continued to cause ashfall in communities within 10 km W and SW throughout the month. Continuous ejection of incandescent blocks rose 200-300 m above the crater and sent material 300 m down the flanks. The Washington VAAC reported a continuous plume of ash detected in satellite imagery and in the webcam extending about 95 km WSW on 8 September at 4.6 km altitude. INISVUMEH reported that the increase in activity during 8 September fed a lava flow that traveled 800 m down Barranca Seca.

The ninth eruptive episode of 2017 began late on 12 September and lasted about 35 hours (figure 79). Pyroclastic flows descended the Seca (Santa Teresa) ravine on the W flank, along with a lava flow that traveled 1.3 km during the episode. Ashfall was reported in Morelia, Palo Verde Estate, Sangre de Cristo, El Porvenir, Santa Sofía, and Panimaché I and II. The Washington VAAC reported that an ash plume extended about 65 km N from the summit on 13 September at 4.6 km altitude. After several days of weather clouds obscuring the satellite images, they reported a plume drifting W on 17 September extending 95 km from the summit. A hotspot intermittently appeared during 13-17 September.

Seven lahars were recorded during September in the main ravines of Fuego, on days 3, 4, 5, 6, 8, 27, and 29, as a result of the unusually large amount of rainfall during the month (1,059 mm) (figure 81). The larger ones at the beginning of the month contained blocks up to 3 m in diameter, and many were warm enough to generate steam with strong odors of SO2. Several roads were damaged.

Activity during October 2017. Overall activity was quieter during October 2017. Background levels of activity included incandescent material rising up to 250 m above the summit and falling a similar distance down the flanks, and ash plumes rising to 4.4-5.0 km altitude and drifting more than 25 km W, NW, and E. Eight to twelve explosions per hour were not uncommon, although 4-6 per hour were more typical. A few of the block avalanches traveled 2 km down the flanks. The communities that experienced persistent ashfall were all located 10-20 km SW, and included Morelia, Palo Verde Farm, Sangre de Cristo, El Porvenir, Santa Sofía, and Panimaché I and II. Due to the wind conditions and increased activity during the first week of October, ashfall was also reported farther away in Guatemala City (40 km NE), Antigua Guatemala, Villa Nueva (30 km ENE) and San Miguel Petapa (35 km ENE). INSIVUMEH reported three increases in explosive activity during the month on 2, 3, and 5 October, but they did not develop into eruptive episodes.

Four lahars were reported on 1, 2, and 4 October in the Seca and Mineral drainages. They carried blocks of volcanic rocks and debris as large as 3 m in diameter and were 6-12 m wide and 1-2 m deep. The Washington VAAC reported a series of explosions on 4 October, after which ash emissions were seen in multispectral imagery at 5.2 km altitude drifting SW that reached as far as 75 km. They reported occasional puffs of ash on 15 October extending up to 95 km W of the summit. By 17 October, imagery showed continuous emissions with an ash plume extending 95 km SSW from the summit before dissipating. A possible ash plume was reported by the Washington VAAC on 31 October extending 45 km W from the summit at 4.3 km altitude.

Activity during November 2017. There were numerous periods of intermittent ash emissions during November. Continuous emissions often drifted 65-100 km or more SW or W at altitudes around 4.6-5.2 km during periods of activity. INSIVUMEH reported that during 2-3 November tremor at Fuego increased. Explosions during the first week averaged 5-8 per hour and ash plumes rose as high as 1.3 km above the crater. Incandescent material was ejected 300 m above the crater, causing avalanches that were confined to the crater. The 11th eruptive episode in 2017 began on 5 November and lasted for two days. Lava flowed 1-1.2 km W down the Seca drainage and 800 m SSW down the Ceniza drainage. Avalanches of material from the ends of the lava flows descended the flanks and reached vegetated areas.

Ashfall was reported in areas downwind in the communities 8-12 km SW including Morelia, Santa Sofia, Palo Verde Farm, and Panimaché I and II throughout the month. Shockwaves from explosions often rattled windows and roofs around the volcano. Avalanche blocks were reported in the Cenizas, Trinidad, Taniluyá and Seca canyons. Multiple VAAC reports were issued on 25 days of November, and multiple daily MODVOLC thermal alerts were issued on 20 days of the month. On 10 November the emissions extended about 275 km WSW from the summit. A lahar during the third week descended the Seca and el Mineral drainages.

Activity during December 2017. Explosions averaged 4-8 per hour during most of December sending incandescent material 200-250 m above the crater. INSIVUMEH reported that the 12th eruptive episode at Fuego in 2017 began on 10 December and, based on seismicity, lasted for about 36 hours. Ash plumes from moderate-to-strong explosions rose as high as 1.2 km above the crater rim and drifted 20 km S and SW. Lava flowed as far as 1.5 km W down the Seca (Santa Teresa), SW down the Taniluyá, and SSW down the Ceniza ravines. Ash fell many times in the communities of La Rochela, San Andrés Osuna, Morelia, and Panimaché I and II. On 12 December there was an average of 10 explosions per hour, generating avalanches in the Ceniza and Taniluyá drainages and ashfall in nearby areas. Ashfall was also reported in San Miguel Dueñas, Alotenango, and Ciudad Vieja (13.5 km NE) on 14 December.

Multiple MODVOLC thermal alerts appeared on 20 days during December, and the Washington VAAC issued 91 reports of continuous or intermittent ash plume activity. During eruptive episode 12 on 11 December, they reported an intense hot spot seen at the crater in satellite imagery despite meteoric cloud cover. For most of the second half of December, either continuous or intermittent ash emissions drifted 100-150 km WNW from the summit before dissipating. The Washington VAAC reported an ash emission on 20 December drifting WNW at 5.8 km altitude that extended over 300 km from the summit. A remnant of the plume was observed almost 450 km away late on 20 December before dissipating. Plumes were repeatedly observed over 200 km from the summit during 20-25 December.

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.

Synonyms

Hunahpu

Cones

Feature Name

Feature Type

Elevation

Latitude

Longitude

Meseta

Stratovolcano

3580 m

14° 29' 0" N

90° 53' 0" W

Basic Data

Volcano Number

Last Known Eruption

Elevation

LatitudeLongitude

342090

2018 CE

3763 m / 12346 ft

14.473°N
90.88°W

Volcano Types

Stratovolcano(es)

Rock Types

MajorBasalt / Picro-BasaltAndesite / Basaltic Andesite

MinorTrachyandesite / Basaltic Trachyandesite

Tectonic Setting

Subduction zoneContinental crust (> 25 km)

Population

Within 5 kmWithin 10 kmWithin 30 kmWithin 100 km

1,373
54,332
1,016,339
7,677,809

Geological Summary

Volcán Fuego, one of Central America's most active volcanoes, is one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between 3763-m-high Fuego and its twin volcano to the north, Acatenango. Construction of Meseta dates back to about 230,000 years and continued until the late Pleistocene or early Holocene. Collapse of Meseta may have produced the massive Escuintla debris-avalanche deposit, which extends about 50 km onto the Pacific coastal plain. Growth of the modern Fuego volcano followed, continuing the southward migration of volcanism that began at Acatenango. In contrast to the mostly andesitic Acatenango, eruptions at Fuego have become more mafic with time, and most historical activity has produced basaltic rocks. Frequent vigorous historical eruptions have been recorded since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows.

References

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography.